Can God be different than what the Bible says?

A resposta para a sua pergunta e de muitas pessoas está na Biblia em 2 Timóteo 3:16 “Toda a Escritura é divinamente inspirada...”

A palavra “Escritura” na passagem acima é outro nome para o livro que hoje nós chamamos de Bíblia. O que o versículo acima nos diz é que toda a Bíblia (“toda a Escritura”), foi divinamente inspirada. A frase “divinamente inspirada” é na verdade uma palavra do texto grego, “theopneustos". Essa palavra é composta pela a palavra “theos” que significa Deus e a palavras “pneustos” que significa respirar. Portanto, quando a Bíblia diz que é “theopneustos”, significa que ela é “inspirada por Deus”, é concepção de Deus, ideia de Deus. Portanto a biblia como chamam hoje em dia foi escrita pelo homem mais inspirada por deus.

The answer to your question and that of many people is found in the Bible at 2 Timothy 3:16 "All Scripture is divinely inspired ..."

The word "Scripture" in the above passage is another name for the book that today we call the Bible. What the above verse tells us is that the entire Bible ("all Scripture") was divinely inspired. The phrase "divinely inspired" is actually a word from the Greek text, "theopneustos". This word is composed of the word "theos" which means God and the words "pneustos" which means to breathe. So when the Bible says it is "Theopneustos", means that it is "inspired by God", it is the conception of God, the idea of God, so the Bible as they call it today was written by man most inspired by God.

Your question uses some terms that mean very different things to different people. The most conflicted term is Christianity itself. Christianity is an umbrella term for literally thousands of denominations that have conflicting interpretations of the Bible. Some denominations adhere to biblical literalism, while on the other end of the spectrum the Bible is subordinate to the personal experience. This spectrum can be found in all the major world religions. Your question is itself worded closer to literalism, and would likely be interpreted very differently by a literalist than by an experientalist.

In addition, you should keep in mind that only one in three Christians reads the Bible every day.

And very few actually know the broader content of the texts, as clerics tend to focus on a selection of verses. Atheists actually have more scriptural knowledge than the average Christian.

For all these reasons, I don't think it's possible to give a "universal" answer to your question. The answers you will get will be the reflection of that person's denomination and scriptural knowledge, but it can not reflect the totality.

Your question is valid, and Christians DO have a ready answer for it. Christians answer life and death questions from Christian point of view, and because the way we answer your question have direct practical relevance to life, we are in the business of answering your question.

But it doesn't belong in C.SE due to the current scoping rules, so Philosophy.SE may be the more appropriate SE for it and there must be Christian philosophers who will answer it. I don't want to leave you empty handed though, hence this short answer.

About your 2 questions below:

What if the God is actually not good and he does not love people, he caused the Flood for fun, would Christianity says: Yes he is still our God for he created us or Let us turn against him for he is no love?

And what if the God in fact did not create our world, it was one of his angels who created our world, would Christianity says: Yes he is still our God for he is the first cause or We should follow and worship this angel instead as the God did nothing for us?

Your two questions above have roughly been asked before (!), in the 1st-2nd century, by the Gnostics. The Gnostics would have AGREED to your conjectural answers, as in the past 100 years we now know much more of who they are and what they stand for. And yes, if the Gnostics's conception of God turns out to be true, then Christians would certainly be disappointed.

But the early church fathers, who trusted what Jesus said about the true God (as personally taught to them by the apostles), KNEW that the Gnostic conception of God is FALSE. This course from the Teaching Company is an excellent intro which also contains early church father's response (especially St. Irenaeus) to the false teaching. Part of the early church fathers's response was to start designating select books as CANON for posterity. The NT canon is the basis of the reasonable axiomatic belief that the Bible's description of God is trustworthy and can be used for us to answer existential questions about life.

The Apostle Paul said this in Galatians:

6 I am astonished that you are so quickly deserting the one who called you to live in the grace of Christ and are turning to a different gospel— 7 which is really no gospel at all. Evidently some people are throwing you into confusion and are trying to pervert the gospel of Christ. 8 But even if we or an angel from heaven should preach a gospel other than the one we preached to you, let them be under God’s curse! 9 As we have already said, so now I say again: If anybody is preaching to you a gospel other than what you accepted, let them be under God’s curse! (Galatians 1:6-9)

These words condition me to expect that powerful, persuasive, lying spirits may enter my life and try to persuade me that the truth is other than what is written in the Bible. They warn me to be prepared and stand fast on what was originally taught.

So to answer your question, there are powerful beings who act and speak in ways contrary to the Bible. They may say they are God, but are not, and I (and steadfast, well prepared Christians) will reject them when they appear and wait for the true God to arrive.

As a new believer (and a scientist), I took this possibility into consideration. Having become a Christian, I was experiencing many benefits in my life - hope, optimism, joy, answered prayers. But were these benefits coming to me from the God as described in the Bible, or some other God who was generously overlooking the fact that I was obeying abd believing the Bible? So I prayed to God that if He exists but that some other religion was the correct one, that He remove his benefits as a sign to me to keep looking. Instead, the blessings have only increased.

You'll forgive me if I center my answer on the Bible: A Christian really has no other recourse. Logic demands that if God exists then He has definitive attributes. Common sense demands that if a truly transcendent, infinite, and eternal being exists there is no way that we (temporal, finite, limited, etc.) could know anything about it's existence or being unless it has revealed itself and we perceive and accept the revelation.

for whoever would draw near to God must believe that he exists and that he rewards those who seek him. - Hebrews 11:6b

This is a fundamental reason why Biblical revelation is necessary for the knowledge of God but it is not the final authority. The Bible's main focus is the revelation of Jesus Christ because it is He who reveals God the Father in whatever detail we mortals are able to grasp.

And the Father who sent me has himself borne witness about me. His voice you have never heard, his form you have never seen, and you do not have his word abiding in you, for you do not believe the one whom he has sent. You search the Scriptures because you think that in them you have eternal life; and it is they that bear witness about me, yet you refuse to come to me that you may have life.- John 5:37-40

There are a great many people who consider themselves to be Christians. Some claim Christianity based upon membership in and practice of a particular denomination or religious system. Some claim Christianity based upon upbringing, having been raised in a Christian household or a Christian nation (if you can conceive of that). But there are those who have and who do actually experience God as Father by the reception of Jesus Christ as Lord and Savior.

because, if you confess with your mouth that Jesus is Lord and believe in your heart that God raised him from the dead, you will be saved. For with the heart one believes and is justified, and with the mouth one confesses and is saved. For the Scripture says, “Everyone who believes in him will not be put to shame.” - Romans 10:9-11

This is the critical difference between human religion and Christianity: Christianity is an actual personal relationship with God. There is a new birth (birth from above) that God brings about when a sinner renounces hope in all other means and cries out in his heart for the blood of Christ to be applied to his account before God. That person is then justified before God by grace through faith in Christ's works rather than their own works and the Spirit of that very same God takes up residence within that person and testifies to the reality of both God and their salvation.

For we ourselves were once foolish, disobedient, led astray, slaves to various passions and pleasures, passing our days in malice and envy, hated by others and hating one another. But when the goodness and loving kindness of God our Savior appeared, he saved us, not because of works done by us in righteousness, but according to his own mercy, by the washing of regeneration and renewal of the Holy Spirit,  whom he poured out on us richly through Jesus Christ our Savior, so that being justified by his grace we might become heirs according to the hope of eternal life. - Titus 3:3-7

It is because of the Spirit of God living within a born again believer (Christian), opening their minds to understand the things of God, and striving within them against their sinful nature so that they can obey in their hearts that a Christian can say that they KNOW God. This is not knowledge in an intellectual sense but in an intimate, relational, and personal sense.

Whoever believes in the Son of God has the testimony in himself. Whoever does not believe God has made him a liar, because he has not believed in the testimony that God has borne concerning his Son. And this is the testimony, that God gave us eternal life, and this life is in his Son. Whoever has the Son has life; whoever does not have the Son of God does not have life. I write these things to you who believe in the name of the Son of God, that you may know that you have eternal life. - 1 John 5:10-13 

As Codosaur has indicated in (his?) answer Biblical literacy within Christendom as a whole is appallingly low so I suppose that in general much surprise will be experienced by everyone when we come face to face with God. In fact, the Lord Jesus will say to many who think that they belong to Him that He never knew them:

“Not everyone who says to me, ‘Lord, Lord,’ will enter the kingdom of heaven, but the one who does the will of my Father who is in heaven. On that day many will say to me, ‘Lord, Lord, did we not prophesy in your name, and cast out demons in your name, and do many mighty works in your name?’ And then will I declare to them, ‘I never knew you; depart from me, you workers of lawlessness.’ - Matthew 7:21-23

And, as the Bible reveals everything that we need to know about God in order to understand our need to be saved by Him and the means He has provided to that end but does not claim to reveal everything that there is to know about the totality of God, it is certain that everyone, even the most faithful born again believer, will learn a great many things when they come fully into His presence.

When I was a child, I spoke like a child, I thought like a child, I reasoned like a child. When I became a man, I gave up childish ways. For now we see in a mirror dimly, but then face to face. Now I know in part; then I shall know fully, even as I have been fully known. - 1 Corinthians 13:11-12

What will not happen is the discovery that God is the opposite of what He has revealed Himself to be in the Bible and in Christ Jesus. We will not discover that God is finite, or petty, or ignorant, or less than good. We will not discover that He is anything like us.

Christians are certain that the Bible is true because the God that inspired the writing of it lives within them. A Christian has the apparently audacious ability to say that they know God AND be correct.

He who comes from above is above all. He who is of the earth belongs to the earth and speaks in an earthly way. He who comes from heaven is above all. He bears witness to what he has seen and heard, yet no one receives his testimony. Whoever receives his testimony sets his seal to this, that God is true. For he whom God has sent utters the words of God, for he gives the Spirit without measure. The Father loves the Son and has given all things into his hand. Whoever believes in the Son has eternal life; whoever does not obey the Son shall not see life, but the wrath of God remains on him. - John 3:31-36