Who judges immorality the church God or Satan?

God has already judged what is immoral. The Bible lists numerous things which God has judged as immoral.

Each congregation also has authority to judge regarding immorality.

1 Cor 5:12, 13states: "Why should I judge outsiders? Aren't we supposed to judge only church members? God judges everyone else. The Scriptures say, "Chase away any of your own people who are evil." (Contemporary English Version (CEV))

Or as The Message (paraphrased version) states: "God decides on the outsiders, but we need to decide when our brothers and sisters are out of line and, if necessary, clean house."