Is the Christian concept of 'forgiveness of sins' psychopathic?
Murder, rape, cheat, steal, then go to church on Sunday to get the slate wiped clean and start all over again on Monday.
How is that NOT insanity?
That's common in all the Abrahamic religions. Don't be bad, unless you get permission (or orders from God or the church) in advance, or unless you beg for forgiveness after you already did it. But hey, as long as you're doing it for YOUR team and not the other teams then you get to keep playing.
No, there are certain things which are unacceptable for many religions, and in this case, Christianity. For example, the 5th commandment states you should not kill. There are case where it may be forgiven (accidents, defense, etc.), but pre-meditated murder shouldn't be forgiven. Also there are boundaries. You shouldn't think of prayer like a cheat code to get out of impending doom.
Everything the OP mentions are basic tenants of good mental health. It's why liberals are always high strung, drama queens, and negative toxic people. They possess no spiritual foundation, no objective meaning, no objective gratitude for life & blessings, and no objective truth. Liberalism & atheism are the perfect storm for poor mental health.