Latin, the use of "dimitto"?

Question

I don't understand "non ei dimitterentur"; （not separated on him？？？）
I took "ei" for "on him". I judged "him" is Christ. "dimitto" means "forgive" immediately before this place, but at this place it seems to mean "send away、let loose, etc." But if so, a contradictionary might arise against the consequent passages.


ut quisquis in Ecclesia eius dimitti sibi peccata non crederet, non ei dimitterentur;
(that any people who don't believe their sins are forgiven in His church might not be separated on Him;)
quisquis autem crederet seque ab his correctus averteret, in eiusdem Ecclesiae gremio constitutus, eadem fide atque correctione sanaretur.
(whoever believes Him, gets corrected, and gets well-ordered in the bosom of the church, and turns away from sins, and by the faith and improvement recovers to health.)
Quisquis enim non credit dimitti sibi posse peccata, fit deterior desperando, quasi nihil illi melius quam malum esse remaneat, ubi de fructu suae conversionis infidus es

(Whoever doesn't believe his sins can be forgiven gets worse in despair. As it were, to him nothing good but bad remains. So he gets an infidel turning away from the fruit of conversion.)

And one more question.
I want to know "quisquis" can be treated as plural. In "quisquis in Ecclesia eius dimitti sibi peccata non crederet, non ei dimitterentur",
the predicate for "quisquis" is the plural "dimitterentur", isn't it?

Answer 1

I think it is as follows:
If you translate dimitto as forgive (really sent away, maybe also taken away)
whoever does not belive that the Church does not forgive his sins (does not send away his sins), his sins will not be forgiven (sent/taken away from him) dimitterentur is plural and passiv but refers to sins - ei refers to quisquis (from him = from anyone who does not believe...) ei does not refer to God.

My Latin is quite a while back and I am not a native English speaker so I hope I made it clear.
It would be easier for me to point it out in German as we have the dativ case which English does not know in that way.