How do you know when you are truly saved, and how do you live as a Christian afterwards?

"[I]f you confess with your mouth Jesus as Lord, and believe in your heart that God raised Him from the dead, you will be saved" Romans 10:9

Now, first of all, you must give up the idea that this sentence above is false. That is the biggest problem you have here. All your questions revolve around the idea that now there is something you have to do to earn / keep / deserve / improve / finish Christ's work on the cross.

If your questions are about how you can deserve to stay saved, go back to Square One. Galatians has a warning for such people:

You who are trying to be justified by the law have been alienated from Christ; you have fallen away from grace. Gal 5:4

If you on the other hand your motivation is that you are bursting with joy and want to serve God, there are some guidelines in the bible:

1. Believe in Him who was sent
2. Have a broken and contrite spirit
3. Knock
4. Pursue righteousness faith love and peace
5. Seek
6. Struggle against the flesh
7. Turn away from wickedness

If it matters, my theological thinking on the topic of justification is influenced by the theological writings of Tullian Tchividjian, who often quotes Gerhard Forde and Martin Luther.

John 3:5-8 describes being born of the spirit. Yet it also simply boils down to the simple point of believing that Jesus died, rose again, is the Son of the living God, and you asking the forgiveness of your sins from Him. The best part about it, is that it is not complex, and is not meant to be complex. Your not required to jump through hoops or read between the lines to understand. It is an observation of mine that people can make things complex, but the word of God is simply the truth.

Jesus answered, Verily, verily, I say unto thee, Except a man be born of water and of the               
Spirit, he cannot enter into the kingdom of God. That which is born of the flesh is flesh;
and that which is born of the Spirit is spirit. Marvel not that I said unto thee, Ye must 
be born again. The wind bloweth where it listeth, and thou hearest the sound thereof, but 
canst not tell whence it cometh, and whither it goeth:so is every one that is born of the 
Spirit

In I Corinthians 15:1 - 2 it is written,

Now I make known unto you brethren, the gospel which I preached unto you, which also ye received, wherein also ye stand, by which also ye are saved, if ye hold fast the word which I preached unto you, except ye believed in vain. - I Corinthians 15:1 - 2

It says that there is a gospel that was preached on to the early Christians which they received and where they stand, and held fast.

You should look for that gospel, not those that are preached by other pastors for monetary gains. As you will not gain anything good with that,

For we are not, like so many, peddlers of God's word, but as men of sincerity, as commissioned by God, in the sight of God we speak in Christ - II Corinthians 2:17

and once you hear that gospel be sure to walk on it.

I hope you find what you are looking for soon. It's really nice to hear that you are concerned on your salvation at your age.

Remember also thy Creator in the days of thy youth, before the evil days come, and the years draw nigh, when thou shalt say, I have no pleasure in them - Proverbs 12:1

Please be careful to follow God's words and not just commandments of blind men,

Let them alone:they are blind guides. And if the blind guide the blind, both shall fall into a pit - Matthew 15:14

Look for God's words, and keep it to your heart dearly.

Thy word have I hid in mine heart, that I might not sin against thee - Psalms 119:11

Please try to visit our preacher's blog. You can also ask him your questions on his twitter account at he can answer your questions much better than me. And he really answers questions sensibly.

In advance: I'll be answering from the Reformed perspective.

You're asking about assurance of salvation. It is quite possible to be saved, but not have assurance of your salvation. That is because justification is by grace through faith (Eph. 2:8-9). That is, we believe we are justified by grace alone through faith alone, but we are not justified on the basis of how well we understand the doctrine of justification by grace through faith!

It is also possible not to be saved, but to be mistaken in thinking you are (Ma. 7:21-23).

So how to tell the difference? How can you know you are saved?

I think it looks different for different people. I have assurance because the Holy Spirit convicts me of sin and drives me back to the cross. This is distinguished from the Devil's accusations, which would attempt to drive me to despair.

I believe it is possible to lose assurance, but it is never possible to lose salvation. That is, if you truly believe in Jesus Christ as your Savior and Lord, then you will be saved.

Now, you're saved from something to something. What are those things? You are saved from hell and to heaven, ultimately. But you are not only delivered fron the guilt of sin (through justification), but the power of sin (through sanctification). Faith is not without works. But our good works (defined as obedience to the law) have nothing whatsoever to do with our justification. Our good works have everything to do with our sanctification. Justification is 100% God, period. Sanctification is 100% God and 100% man. If your faith is genuine, then it will work itself out in fear and trembling.

Assurance can come from the works God is working in you, from the precious promises in the Bible, and from the working of the Holy Spirit in you, among (probably) many other things.

The prophet Jonah says that "Salvation is of the Lord." And it's precisely because it is of God, and not of me, that I can have assurance of salvation. Can I lose my salvation? Wrong question! The better question is, "Can God lose my salvation?" And to ask that question is to answer it.