The biblical authors long ago disputed about this. The intellectual tradition of ancient Israel, the Wisdom tradition, is represented in the Bible by two distinct lines of thought. The first, represented by the book of Proverbs and several of the Psalms, suggests that God and God's way are readily available to our minds. The truth is simple and accessible. God has revealed it to us, and we can understand it.
Faith is a matter of memorizing truth and living by it.
But this view is too simplistic for the other line of thought in the Hebrew wisdom tradition, represented by Ecclesiastes and Job, which want to say God is beyond our understanding and we should be more intellectually humble than to claim to know the ways of God. The Bible sets forth both of these ideas in a balancing paradox. Consider the story of Job, an ancient morality tale about faithfulness into which a later poet inserted a lengthy challenge to popular orthodoxy. Job is a good and wealthy man, faithful to God and upstanding. Job is only faithful because his life is easy.