Man in his sinful condition could never merit heaven anymore than he could create himself. It is only man's sinful pride that tells him something different.
To be sure, Paul wrote very heavy with theological truth but always with the heart of a pastor, as one always concerned about the well being of God's people.
If knowing Jesus is not intensely personal then you do not know Jesus at all. If knowing Jesus does not dis-annul all other things as a mean of getting to heaven, then you do not know Jesus at all. If knowing Jesus does not make the way to heaven cleknowing_jesusar, then you do not know Jesus at all. If knowing Jesus does not reveal empty religion for what it is - empty, then you do not know Jesus at all.
Because a believer has assurance of salvation he is kept from sinning, and when he does not sin he is given an assurance of salvation. Therein lies a victorious cycle that no believer can afford to be without.