Our Faith will never be true unless it is united to that of St. Peter and the Pontiff, his successors.
Alphonsus LiguoriSt. Augustine and St. Thomas define mortal sin to be a turning away from God: that is, the turning of one's back upon God, leaving the Creator for the sake of the creature. What punishment would that subject deserve who, while his king was giving him a command, contemptuously turned his back upon him to go and transgress his orders? This is what the sinner does; and this is punished in hell with the pain of loss, that is, the loss of God, a punishment richly deserved by him who in this life turns his back upon his sovereign good.
Alphonsus LiguoriNew revelations regarding faith or morals ... have always been abhorred and challenged in the Church ... Hence, the Sovereign Pontiffs, the Councils, and the Fathers have been most careful to reject all novelties or new doctrines on matters of faith which differed from those already received.
Alphonsus Liguori