Belief/faith in Him is what seals the person by the Holy Spirit. Not the institution which may prevent the believer from actually going on from milk to strong meat. If satan cannot prevent a believer from believing, the last thing he wants is that believer bringing forth more for the harvest. I was at the graveside of an old friend, a man who brought me to Christ decades ago. He died two Sundays ago. His graveside service was officiated by Mormons because he fell into Mormonism within ten years of being Born Again. I know of not one more person he led to the Lord once he fell into Mormonism with his wife. I watched that religion change him, dull his light, cast his mind into endless confusion. But he will be in the Rapture of the Church, because the Church is something God fashions, not the works of. Faith is the key which opens the heart to the Promises of God. During the ages when the Catholic Church was the only Christian message, God was saving believers, even as the rituals and incantations were blunting the growth of same.
Having faith in your faith does not save ..JESUS CHRIST SAVES ...Having faith in a false jesus does not save..