Had it not been for God guiding the Church fathers, you would be reading the Gospel of Thomas in the morning.
It was God guiding His church. It is the Holy Spirit who protects us. And it is the Holy Spirit who confirms within us what is or is not scripture.
Please remember that in the end, we stand before God as individuals:
5 One person esteems one day as better than another, while another esteems all days alike. Each one should be fully convinced in his own mind. 6 The one who observes the day, observes it in honor of the Lord. The one who eats, eats in honor of the Lord, since he gives thanks to God, while the one who abstains, abstains in honor of the Lord and gives thanks to God. 7 For none of us lives to himself, and none of us dies to himself. 8 For if we live, we live to the Lord, and if we die, we die to the Lord. So then, whether we live or whether we die, we are the Lord’s. 9 For to this end Christ died and lived again, that he might be Lord both of the dead and of the living.
10 Why do you pass judgment on your brother? Or you, why do you despise your brother? For we will all stand before the judgment seat of God; 11 for it is written,
“As I live, says the Lord, every knee shall bow to me,
and every tongue shall confess to God.”
12 So then each of us will give an account of himself to God. - Romans 14
Please notice that Paul didn’t tell them to ask the Vicar of Christ, the Infallible Peter...