The answer
St. Basil the Great says, “He who sins with his sister should remain outside the church gates for three years until he realizes the seriousness of what he committed, asking those entering the church to pray for him that he may find grace before God. Three years later, he joins the congregation of the listeners, and after the readings and the sermon he is to be expelled from the church and not allowed to attend the Liturgy of the Faithful. Three years later, he can rejoin the community.”
Fr. Tadros Yacoub Malaty