What's the name of this doctrine and (when) did the Eastern Orthodox Church condemn it?

Question

"God is merciful and He wants all people to be saved, thus, all the humans, even the worst ones, having fully redeemed themselves from their wrongdoings by spending some adequate time in the hell, will finally make it to the paradise..."

What's the official name of this doctrine? I heard something like "optimistic eschatology", but I am not sure.

And also, I heard that the Eastern Orthodox Church has condemned this doctrine as a heresy. If it's true, when and where (on which counsel) did this take place?

Answer 1

I believe you are looking for the theology called "Universalism".

I'm not sure that it has been explicitly declared a heresy, but the Catholic, Orthodox many Protestant churches have made formal declarations that are in disagreement with it, so they presumably do consider it a heresy. Look at the 'disagreements' section of the article.

Answer 2

The term you're looking for is apocatastasis. I would argue that it has not officially been condemned as a heresy, although the primary teacher of apocatastasis was condemned as a heretic at the 5th ecumenical council (Origen). See my response to your other question about universalism for more information.