"For Catholics to deny Communion to ALL other Christians who happen to be Prostestant ..."
Actually, the Holy Roman Catholic Church denies the Sacrament to ALL who are not in a State of Grace, including Catholic sinners. Had you attended the Sacrament of Confession and assuming you were validly baptized and been given absolution, you could have taken part in the Sacrament of the Mass. When I am in a state of mortal sin, I cannopt ntake the Sacrament. Period. It is simply against the Gospel - the Literal Word of God - to eat of the Flesh of Our Lord while in a state of serious sin. If you need references directly taken from the Holy Writ, simply ask, we'll provide them.
And what are these other "mortal" sins Jesus never taught, since Scripture only says one, blasphemy of the Holy Spirit, keeps you from God?