One of the philosophical legacies Americans carry around in our mental baggage is a Lockean "common sense" construct.
A favored offshoot of that is the phrase "seeing is believing." Which generally means that we view ourselves as hard-bitten realists, and that we believe nothing until we've seen clear, convincing evidence for it.
And taken to logical conclusions, such a view is death to the Christian faith. Fortunately, most of us are inconsistent. Even though we pretend that seeing is believing, we act otherwise.
St. John of Damascus was blessed to have lived and thought before common sense philosophy came into being. His hymn The Day of Resurrection spoke a different way (verse 2, LSB):
"Let hearts be purged of evil, That we may see aright,
The Lord in rays eternal, of resurrection light
And, list'ning to His accents, May hear so calm and plain,
His own 'All hail!' and, hearing, May raise the victor strain."
Note the sequence: our hearts are purged from evil, which enables us to see. "Seeing is believing" works -- but only in the most technical, material senses. "Seeing is believing" (like Occam's razor) is death to any religious faith, Christian or otherwise. The reality is that in the most important things in life, we believe and then -- because we have been given the gift of believing, of trusting -- we see the reality of God and the creation.