“Does the church practice excommunication and if it does, then on what grounds is it practiced?”

Bishop John’s Answer:

Excommunication is the most severe penalty that the Church imposes under very special, even sad, circumstances. All penalties are meant to be medicinal and remedial. It is the hope of the Church that a person will cooperate with the Holy Spirit and have a change of heart so as to avoid such a severe penalty. Serious sin can break our intimacy with the Lord, but, in His mercy, he provides us with the sacrament of reconciliation whereby we are restored to His love in full measure. The events that can bring about excommunication have to do with a denial of the faith or a deliberate rejection of legitimate church authority.