Do you really find it so impossible to not sin? [ honestly, he assumed that dazai's superior intelligence would be a better regulator for those impulses but, well. he has been wrong at times so he'll just add this as one more of those rare times. ]

Your arm doesn't bother me. [ meaning yes, he still wants it. ] And you can't really confess by proxy, you'd need to go to confession and kneel. I would absolve you but only if you promised to behave, even if God's love is unconditional one should never seek to abuse it.

[ which hilarious given all that fyodor is doing but yanno ]