Before I start, I think we need to get a baseline here.
there are some people who think you can just "believe" jesus died on the cross, say a "sinners" prayer and your in,
I am NOT one of those people.
James makes it clear that mere belief will not save anyone "for even demons believe and tremble" It takes more than actual belief, it takes "true faith" And those who claim to believe but have a "dead" faith (proven by the fact they are not doing the words true faith will produce) show their belief was in vein.
John states that those who believe are born of God, Yet he makes a distinction by saying it is "faith" that gives us the power to believe. (and also the power to do righteous deeds, and LOVE) differentiating again the difference of those who believe, yet have no faith, who are not born again.
Paul speaks to those who "believe" but are trying to be justified by righteous deeds (works) or by the law (The traditions of the law, and the letter of the law, or obeying commands, and if fail, doing something to make up for the failure) That their belief will not save them. For their faith is not in Christ, but their works.
Then we have a third type, A person who claims to believe, may even be a part of the church for awhile, then decide this "Jesus thing" is not real, and become "anti-Christ" (chose not to believe at all. And John makes it clear., these people departed to prove thet they never were truly a part of the church.
so you see we have 4 types of people.
1. Believes in Jesus, but does not believe they are sinful, this you will see no change in their life, they live as they did in the world. These people were addressed by James and Jude and called Licentious. These would be people who say the sinners prayer, but did not mean it, because they really did not have faith it was real, Proven by the fact, they still live as they did before (no changed life thus no true repentance) and show no works. Jude condemns these people in a harsh way, staing the turn the "grace of God into licentiousness" The deny God by their actions.
2. Believe in Jesus, but add works of some kind to the gospel in an attempt to help Jesus in our salvation. (we must do something to make up for our wrongs, it can't be free)
3. Believe in Jesus for a time, then decide that Jesus is not real. and leave the church altogether. In other words, Jesus was a fad they were going through,
4. Those of true faith, who believe God when he said "all have sinned and fall short (literally missed the mark, which was the law) of the glory (perfection and just requirement he gave mankind to be able of our own merit get to heaven, or again the law) and thus are separated from God by the just penalty imposed by God for those who do not meet the just requirement of the law. (Death).
That we, being guilty are rightly condemned, and we can do nothing to make up for this condemnation, For the only penalty (eternal) is death, thus only death can be given as payment,
That Christ, came to earth, fulfilled the just requirement of the law (no sin) and suffered death (spiritual) on the cross. "My God My God why have you forsaken (departed) from me" This was his spiritual death, where Gods wrath we deserve was poured on him on our behalf.
That Christ then said "it (the plan of salvation) was finished (completed) then he died physically, and three days later was risen again (the firstfruits) and that because of this sacrifice, he is offering all mankind the gift of restoration to him based only on his sacrifice on the cross. And that whoever trusts God and receives this "gift" he is offering will receive eternal life, and be resurrected by him (not delivered to him) on the last day.
These people, Who truly trusted through true repentance (a change of heart) will have a changed life (might be gradual but will change) will show works that prove their repentance and faith was real, But will not be sinless.
I find it amazing, that the licentious Christian will call me a legalistic, works based condemning spirit because I question their salvation because I see no changed life or works. and those who believe that works (of any type) are essential for salvation will call me a person who states that if Hitler said the sinners prayer before he brutally murdered millions of Gods chosen, and millions of others, he is saved and in heaven, which is preposterous and ridiculous, and shows you do understand what it is I believe.