My grandfather (and many others, no doubt) used to turn a particular phrase that I still remember to this day:
Don’t believe anything you hear and only half of what you see.
Other similar phrases that we often hear bandied about are these: “I’ll believe it when I see it,” and “seeing is believing.”
I believe that my grandfather’s phrase was nearer the truth (although not theologically correct by a long shot – not even close!). Biblically speaking, seeing is not believing; in fact, the opposite is usually true – faith almost always precedes perception.
And how does the Bible define faith? Well, Hebrews 11:1 (ESV) provides a pretty clear answer:
Now faith is the assurance of things hoped for, the conviction of things not seen.
Also, according to this passage from 2 Corinthians 4, the only things that matter (and endure) from a spiritual perspective are those which completely bypass our human perceptions:
Meditate on that, friends. Seeing is not everything!