I also believe that this gives people a wrong impression that once we’ve said a “sinner’s prayer” or something similar, that we can live however we want because God has forgiven us everything.
While a “sinner’s prayer” can play an important part in someone coming to the Lord in repentance, it isn’t a golden ticket to get into heaven for nothing.
From what I understand, our past sins are forgotten when we come to the Lord in repentance when we are first born again.
Our present and future sins will be forgiven if we confess and repent of them once we are made aware of them, which could happen in different ways for different people, but always by the Holy Spirit.
(I’m sure there are sins we commit that we do not know are sins yet, and the Lord shows us grace by not condemning us for those, but will eventually show us they are sin. That’s when we need to confess and repent of them.)
If all of our present and future sins were forgiven, then why would 2 Peter 3:9 tell us this: “The Lord is not slack concerning his promise, as some men count slackness; but is longsuffering to us-ward, not willing that any should perish, but that all should come to repentance.”
This verse is being spoken to believers, not unbelievers.
Also, look at what Romans 8:1 tells us: “There is therefore now no condemnation to them which are in Christ Jesus, who walk not after the flesh, but after the Spirit.”
Those who believe they are saved just by saying a little prayer, or by being told they are saved just because they believe are not getting the full story. It is those who are walking after the Spirit who have no condemnation. If you are walking after the flesh, you are basically willfully sinning because you think that whatever you do will be forgiven.
Also, be mindful of this verse. If we confess our sins, he is faithful and just to forgive us [our] sins, and to cleanse us from all unrighteousness.” 1 John 1:9*