Will we retain the ability to sin after we die and go to heaven?
If you answer “yes”, then sin will never be fully eradicated, which is contrary to Paul who said we will become incorruptible at the resurrection (1st Cornthians 15:52), and contrary to the Book of Revelation teaching that humans who don’t sin are inside the New Jerusalem, and those who sin are outside (Rev. 21:14-15).
If you answer “no”, then since God doesn’t require the now-departed saints to have freewill in order to accept their love and worship as authentic, then he could have made Adam and Eve with the same type of will these now-departed saints have (authentically loving God, but incapable of choosing evil), and the whole problem of evil could have been solved before it started.
Somebody will say God uses human evil to achieve a greater good, but the question is not whether God can use human evil to achieve a greater good, but why God desired to give humans freewill when that was not the only way to achieve all his holy purposes.
The only way out of this argument is to say God desired for evil to happen, and that makes you a nasty Calvinist, serving a Hitler-type god who tells people to stop sinning, while intending that they continue sinning anyway.