The fundamental thing is God’s gift of His love. And the heart has reasons that reason doesn’t know. That’s the basic thing about faith. And to go further than that whom do we depend upon? The prophets, Jesus Christ, the Apostles and so on. It’s a historical problem. And you have to do the history not as though you’re studying a life of Christ in the same way as you write a life of Julius Caesar but in the light of faith, in the light of loving God above all. God has flooded our inmost heart with His Love through the Holy Spirit He has given us. Romans 5:5. And you carry out your studies in the light of that Love.