My Strange Theory/Heresy of Justification From the Psalms

I realized as I read Lewis' reflections on the Psalms today that I could never stand before Holy God and be judged righteous. "Enter not into judgement with Thy servant, for in Thy sight shall no man living be justified." (Psalm 143:2).

My theology therefore in trying to dodge around Trent which merely says anathema to those who believe justification comes from the SOLE imputation of Christ's righteousness. So I tend to theorize and teach this version (probably heretical) of justification, probably the only justification theology based almost solely on the Psalms.

So we already have Psalm 143 saying that no living person will be deemed righteous by himself (or herself). Then in Psalm 32 "Happy are those whose transgression is forgiven, whose sin is covered. Happy are those to whom the Lord imputes no iniquity". So now it is the idea that the sin of the individual is washed away in Baptism and by faith and repentance actual sin is imputed to Christ on the cross (somehow it time travels?). So then we have an individual who has no sin on their soul, they are forgiven (Ps 51:1). Then we have God judging a person only on their merits which he has given them by grace and worked through them (Phil 2:13).

I also tend to assume that the only mortal sin is that of not having faith. I think this places me somewhere between Catholicism and Arminianism.

All this is my personal theology - officially I've submitted to that of the Roman Catholic Church

But on judgment day I think the only words I will be able to get out are those of David:
"according to your abundant mercy
blot out my transgressions." - Ps 51

I've just read a funny thing on the Catholic Encyclopedia under Justification it says:
"We have seen that Protestants claim the following three qualities for justification: certainty, equality, the impossibility of ever losing it. Diametrically opposed to these qualities are those defended by the Council of Trent (sess. VI, cap. 9-11): uncertainty (incertitudo), inequality (inaequalitas), amissibility (ammisibilitas)."

Why would anyone defend uncertainty, inequality, and amissibility. Like I know the whole 'they're true' or 'they're biblical' argument works, but just at a personal level, I want to know what kind of people think about the gospel and think of those concepts and thinks they're worthy of a fight to defend. Who loses sleep at night over the thought that some are content and certain in their trust of God's grace. It boggles my mind...