What were the nice things Jesus Christ did in his life that he is loved by so many people around the world?

Short answer

You are perfectly right, that in the Christian religion, there is no compulsion. God, through Jesus Christ, shows us his love for us, wants us to be His children, BUT gives us full freedom to reject the offer. But why would we reject the offer, once we realize that the only person who is capable to fix our brokenness is our own Creator? Why reject Jesus who demonstrated that he is a true friend by giving up his own life for us (John 15:13)?

One honest answer is that we are afraid of commitment or that we prefer to do things our way. So God lets us do that for a while, until we realize it's not working. Like the story of the prodigal son, once we're tired of doing things our own way, we can go back to our true Father in heaven through Jesus and let the Holy Trinity comes into our heart to fix us to be more loving and thus have a more fulfilling life.

I am glad that you recognize how Jesus is loved by so many in the world, and that's because he DOES love us first, and waiting for our response.

Jesus's greatest work: invitation for reconciliation, in gracious humility

Christianity teaches that Jesus is God's beloved Son, who left His throne in heaven to come to earth 2000 years ago (Phil 2:6-8) to be born as a regular baby in the manger (a lowly place, where animals eat from) and then grew up among the persecuted people of his race (the Jews) in the remote corner of the Roman Empire. Although his Father is the creator of our universe who is all powerful (witness the galaxies and stars), as a human being he was not pretentious but invited everyone, even the most despised by the society at the time (such as lepers, prostitutes, and tax collectors), as long as the we are willing to repent from our rebellion against his Father (because we feel in our heart / conscience that every wrongdoing we do ends up making us feel guilty before God).

How did Jesus invite us? He showed how his Father is serious in forgiving us by dying on the cross for us as a lonely, tortured, and despised man, but YET still forgave his enemies who condemned him to shameful death. The greatest work shown by Jesus was humbling himself that way despite being the Son of the all powerful God of the universe so that we are no longer afraid of this God (who can crush us like a bug if He wants to) because Jesus was immobile and nailed at the cross (his hands are tied). It is also a lot easier for us to accept Jesus's invitation "Come to me, all who are hungry and thirsty, for I am the Bread of Life (John 6:35) and the Living Water (John 4:10)", because:

1. We can see Jesus at the cross with horror as a mirror of the ugliness of our deep rooted tendency to sin and of our sins, highlighting our need to be saved from our condition.
2. By offering peace from this posture of tortured helplessness, it is a lot easier to lay down our pride of needing help, which is a necessary posture for us to receive the offer of peace from the God of the universe and to allow God to start working the cure in our heart.

How do we accept the invitation?

The 4 main acts are these:

1. Believe that God is our Father in heaven who loves us so very much (John 3:16-17) that He is willing to forget any grudge and set aside his wrath from our wrongdoing against Him because His Son has already died for us to "pay" for our sins (in other words, making Jesus our Savior) with the expectation that we MUST then forgive people who hurt us (Matt 6:14-15) and imitate his humility and graciousness (Phil 2:3-5).

2. Remove our allegiance to any earthly ruler (such as the king of your country, the rich / powerful people who can make you do bad things, or the authorities of any other religions) even if that could result in their hating us because we are no longer their friends (John 15:18-19). In exchange we need to reorient our life wholeheartedly to make Jesus our new King and our best friend. This includes a commitment to obey Jesus's New Covenant commandments (the highest commandment being love, John 13:34-35) as the highest ethical principles above all human laws and all cultural expectations (such as pursuing the American dream). In this way we become citizens of God's Kingdom which is above any other spiritual powers and country governments (John 18:36).

3. Join a local Christian church to be baptized (John 3:5), to study the Bible, and to celebrate the Lord's supper regularly. By joining a community of believers we can practice love and also become the means to spread the gospel to those who haven't heard or received it, as the Kingdom ambassadors (Matt 28:18-20). As a collective who love and serve one another, we show the world how "life in the Kingdom of God" looks like, and spread the influence of that Kingdom to convert violence to peace, despair to hope.

4. Unite our spirit with God's Son, Jesus Christ, beginning with baptism thereby sharing His death, suffering, resurrection, love with our fellow believers, compassion for the world, grace flowing from the vine to produce spiritual fruit (John 15:1-17), and future glory in resurrection of the body after we die. In this way we become Jesus's brothers and sisters and children of the Father in heaven by adoption (Rom 8:15-17), living a life of true freedom in the Spirit (Gal 5).

I want to know what nice and good things Jesus did in his life on earth that he is loved by so many people in the world

He died. Sure, there's some healing and ministering to the poor and whatnot, but really, it's the dying that matters.

The problem with your question is that, other than dying, what Jesus did is missing the point. It's about what Christ does (present tense) for us, which is to reconcile us sinners with the Father. Without Christ, we rightly stand condemned of our failure to live up to God's expectations (perfect love and perfect obedience). But "God so loved the world, that he gave his only Son" to take upon himself the punishment that is rightly ours, "that whoever believes in him should not perish but have eternal life" (John 3:16).

Oh, and... to show His power over death, and to show that His sacrifice is sufficient and certain, He rose from the dead.

Rightly, we ought to love Christ (and God) because He made us, and because He first loved us (1 John 4:19). But we're humans, selfish by nature, who owe Christ a debt of gratitude for saving us from eternal condemnation. If someone saved you from some significant harm in this life, would you not be grateful? How much more grateful are those who recognize the magnitude of what Christ has done for them!

Please, find some overviews of Christianity and read them. I would also strongly encourage you to read Genesis 1-11 and at least one of the gospels. (Ideally, you should read the whole Bible, but start with those...) If possible, I'd also encourage you to find an actual believer to talk to; I get the feeling those may be scarce in your area.

If in my country I denounce God, I would be jailed

All I can say is that this is tremendously unfortunate. No one can be forced to love God, and attempts to do so are likely to have the opposite of the desired effect.

What were the nice things Jesus Christ did in his life that he is loved by so many people around the world?

• He died for our sins!

Indeed, under the law almost everything is purified with blood, and fwithout the shedding of blood there is no forgiveness of sins. - Hebrews 9:22

• Jesus took on human nature by the power of the Holy Spirit.

9-12 What we actually see is Jesus, after being made temporarily inferior to the angels (and so subject to pain and death), in order that he should, in God’s grace, taste death for every man, now crowned with glory and honour. It was right and proper that in bringing many sons to glory, God (from whom and by whom everything exists) should make the leader of their salvation a perfect leader through the fact that he suffered. For the one who makes men holy and the men who are made holy share a common humanity. So that he is not ashamed to call them his brothers, for he says: ‘I will declare your name to my brethren; in the midst of the congregation I will sing praise to you’.

13 And again, speaking as a man, he says: ‘I will put my trust in him’. And, one more instance, in these words: ‘Here am I and the children whom God has given me’.

14-18 Since, then, “the children” have a common physical nature as human beings, he also became a human being, so that by going through death as a man he might destroy him who had the power of death, that is, the devil; and might also set free those who lived their whole lives a prey to the fear of death. It is plain that for this purpose he did not become an angel; he became a man, in actual fact a descendant of Abraham. It was imperative that he should be made like his brothers in nature, if he were to become a High Priest both compassionate and faithful in the things of God, and at the same time able to make atonement for the sins of the people. For by virtue of his own suffering under temptation he is able to help those who are exposed to temptation. - Hebrews 2:12-18

• Jesus forgave sins.

9 Jesus got into a boat, crossed the sea, and came to his own city. 2 Some people brought him a paralyzed man on a stretcher.

When Jesus saw their faith, he said to the man, “Cheer up, friend! Your sins are forgiven.”

3 Then some of the experts in Moses’ Teachings thought, “He’s dishonoring God.”

4 Jesus knew what they were thinking. He asked them, “Why are you thinking evil things? 5 Is it easier to say, ‘Your sins are forgiven,’ or to say, ‘Get up and walk’? 6 I want you to know that the Son of Man has authority on earth to forgive sins.” Then he said to the paralyzed man, “Get up, pick up your stretcher, and go home.”

7 So the man got up and went home. 8 When the crowd saw this, they were filled with awe and praised God for giving such authority to humans. - Matthew 9:1-8

• Jesus on several occasions promised eternal life in heaven to those who believe...

• Even while on the Cross he forgave his executioners.

Jesus said, “Father, forgive them, for they do not know what they are doing.” And they divided up his clothes by casting lots. - Luke 23:34

Christ Crucified (Velázquez)

• Jesus cured the sick and healed the lame.

Large crowds came to Him, bringing the lame, the blind, the crippled, the mute, and many others, and laid them at His feet, and He healed them. - Matthew 15:30

• He fed the hungry.

Jesus Feeds the Five Thousand

13 When Jesus heard what had happened, he withdrew by boat privately to a solitary place. Hearing of this, the crowds followed him on foot from the towns. 14 When Jesus landed and saw a large crowd, he had compassion on them and healed their sick.

15 As evening approached, the disciples came to him and said, “This is a remote place, and it’s already getting late. Send the crowds away, so they can go to the villages and buy themselves some food.”

16 Jesus replied, “They do not need to go away. You give them something to eat.”

17 “We have here only five loaves of bread and two fish,” they answered.

18 “Bring them here to me,” he said. 19 And he directed the people to sit down on the grass. Taking the five loaves and the two fish and looking up to heaven, he gave thanks and broke the loaves. Then he gave them to the disciples, and the disciples gave them to the people. 20 They all ate and were satisfied, and the disciples picked up twelve basketfuls of broken pieces that were left over. 21 The number of those who ate was about five thousand men, besides women and children. - Matthew 14:13-21

• Before ascending to the Father, Jesus promised to send a Helper to the Followers of the Way. He would not leave the Early Church orphans.

15 “If you love Me, keep My commandments. 16 And I will pray the Father, and He will give you another Helper, that He may abide with you forever— 17 the Spirit of truth, whom the world cannot receive, because it neither sees Him nor knows Him; but you know Him, for He dwells with you and will be in you. 18 I will not leave you orphans; I will come to you. - John 14:15-18

In the end , Jesus didn’t many more wonderful and nice things for others. The last words of St. John leads us to contemplate what other marvellous things Jesus may have done while on earth.

Jesus did many other things as well. If every one of them were written down, I suppose that even the whole world would not have room for the books that would be written. John 21:25

16 For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life.

17 For God sent not his Son into the world to condemn the world; but that the world through him might be saved. (John 3:16-17)

Christians believe that Jesus Christ is the Son of God and Savior of the world, who makes eternal life possible.

Those who spent years with Jesus while he ministered to people wrote that:

"God anointed Jesus of Nazareth with the Holy Spirit and power, and he went around doing good and healing all who were under the power of the devil, because God was with him. We are witnesses of everything he did in the country of the Jews and in Jerusalem. They killed him by hanging him on a tree. But God raised him from the dead on the third day and caused him to be seen... by us who ate and drank with him after he rose from the dead. He commanded us to preach to the people and to testify that it is he who God appointed as judge of the living and the dead. All the prophets testify about him that everyone who believes in him receives forgiveness of sins through his name." (Acts 10:36-43)

Jesus didn't just "do nice things". He chose to suffer and die an appalling death so that God's righteous judgment of sin could be poured out on him, the sinless one, on that tree of crucifixion. After he was risen from the dead, his followers understood that this proved his claim to be true - that he is the Son of God. Read Romans 1:1-6 along with Hebrews 1:1-4.

How Jesus the Christ opened up God's forgiveness to those who repentantly trusted in his finished work on the cross is too massive a subject to go into here, but his resurrection from the dead is the crux of Christianity. It is realisation of this miracle of grace that causes people to bend their knees in Jesus' name and to place all their faith in him.

While on earth, Jesus drew people with cords of love. While in heaven he still does the same. There is no coercion, no force. If the love of God in Christ is not enough to attract people, nothing else will 'work'. Those who discover the Christ of the New Testament see how he is the greatest gift God could ever give humanity. God could give nothing greater than his own beloved Son. Willingly receiving him by faith is what turns people into Christians, and nothing in all creation can then separate them from the love of God that is in Christ. Read Romans 8:31-39.

Once you soak up what the New Testament says about this Jesus Christ, it should dawn on you just how lovely he is; further, that he's alive today, interceding for those who turn to him in faith, and that he's coming back to usher in the Day of Resurrection and Judgment. He doesn't just make God's forgiveness, and eternal life "a possibility"; it became a reality at the cross and via the empty tomb. All who put total faith in the Christ of scripture come to love him more than anyone or anything else here on earth, because his love for them is the greatest love there ever can be. And it's totally undeserved. Such love!