“But Abraham said, ‘Moses and the prophets have warned them. Your brothers can read what they wrote.’ “The rich man replied, ‘No, Father Abraham! But if someone is sent to them from the dead, then they will repent of their sins and turn to God.’ “But Abraham said, ‘If they won’t listen to Moses and the prophets, they won’t be persuaded even if someone rises from the dead.’”
I find encouragement from this verse that the Bible and the Old Testament are enough to know God. Of course there is much more available – nature, art, literature, humanity, good, evil. You do not have just one source, but if you want to hear God directly, there is no better place. And so when I have doubts or less trust, I find the solution in the parable of Jesus, and I try to get my eyes on the pages and my head into the word.