The prayer of the faithful will save the sick, and the Lord will raise him up. And if he has committed sins, he will be forgiven.
James 5:16 Confess your trespasses to one another, and pray for one another, that you may be healed. The effective, fervent prayer of a righteous man avails much.
All unrighteousness is sin, and there is sin not leading to death.
1 John 5:16 If anyone sees his brother sinning a sin which does not lead to death, he will ask, and He will give him life for those who commit sin not leading to death. There is sin leading to death. I do not say that he should pray about that.
If the sins are committed before we come to the knowledge of the truth, the sins can be forgiven.
Hebrews 5:13 For everyone who partakes only of milk is unskilled in the word of righteousness, for he is a babe.
For even adults are considered babes in faith if they have no knowledge in the word of righteousness.
Hebrews 5:12 For though by this time you ought to be teachers, you need someone to teach you again the first principles of the oracles of God; and you have come to need milk and not solid food.
For if anyone who come to the knowledge of the truth and again If we give up and turn our backs on all we've learned, all we've been given, all the truth we now know, we repudiate Christ's sacrifice and are left on our own to face the Judgment
Hebrews 10:26-27 For if we sin willfully after we have received the knowledge of the truth, there no longer remains a sacrifice for sins, but a certain fearful expectation of judgment, and fiery indignation which will devour the adversaries.
Those are the sins leading to death - the unforgiven sins!