I’m confused about believers in Heaven, judging angels. What wrong will the angels have done to be judged, if Satan has been vanquished, along with sin?
First lets clarify that even with Satan bound there will still be sin on earth during the millennium.
You are referring to 1 Cor. 6:3 where Paul said since the Church will be judging angels we should be able to settle matters within the body.
The Bible doesn’t say what angels we will judge, but does give us the following examples of angels who are destined for judgment. Rev. 12:4 speaks symbolically about the dragon’s tail sweeping a third of the stars out of the sky and flinging them to earth. Many scholars interpret this as describing Satan’s rebellion and how a third of the angels rebelled with him.
2 Peter 2:4 talks about angels who sinned and are being held in gloomy dungeons for judgment, and Jude 6 tells of angels who took on human form being held for judgment. Genesis 6:4 says these angels married human women and produced hybrid offspring we call the nephilim.