All they have to do is commit a mortal sin and not go to confession. They will be separated.
Your answer makes the most sense to me. Thanks.
One chooses to Excommunicate himself/herself from church by ACTIVELY, VEHEMENTLY and WITHOUT REPENTANCE, opposing and denying the teachings of the church.
Well, in this case, many of our catholic politicians who support abortion, gay marriage, etc. have already separated from the church.
But then, the question comes up — what if these people PUBLICLY oppose church teachings but go to mass anyway? Should they be given Holy Communion?