Interesting that the Bible addresses this in two ways. It says that the evidence of God is clearly seen, and that the evidence of God is not seen. It depends on where I am standing.
Romans 1:18-23 says that God’s wrath is revealed against ungodliness and unrighteousness of those who “suppress the truth in unrighteousness, because what may be known of God is manifest in them, for God has shown it to them. For since the creation of the world His invisible attributes are clearly seen, being understood by the things that are made, even His eternal power and Godhead, so that they are without excuse, because, although they knew God, they did not glorify Him as God, nor were thankful, but became futile in their thoughts, and their foolish hearts were darkened. Professing to be wise, they became fools, and changed the glory of the incorruptible God into an image. . . .”
Psalm 19:1 says the same thing, “The heavens declare the glory of God; and the firmament (expanse of heaven) shows His handiwork.”
Like electricity and the wind (both invisible), people know the existence of God by what He does. Those who deny that evidence do it, not because they are blind and cannot see it, but because they do not want to glorify Him or be thankful. Instead, they make up false gods and idols, and God, in wrath against that unrighteousness, lets them walk out of the light they had and into darkness.
I used to think that the farther a person walks away from this evidence of God’s handiwork, the more blind they become to spiritual realities. Now I realize that the darkness or oblivion to the things of God is always related to matters of the heart, not lack of evidence. God can be found, but many people don’t want to find Him. Jesus gave the reason in John 3:18-20.
He who believes in Him is not condemned; but he who does not believe is condemned already, because he has not believed in the name of the only begotten Son of God. And this is the condemnation, that the light has come into the world, and men loved darkness rather than light, because their deeds were evil. For everyone practicing evil hates the light and does not come to the light, lest his deeds should be exposed.It is never ignorance or lack of evidence that keeps a person from knowing and believing that God exists; it is that sinful I will run my own life determination. Again, if a person wants to find God, He is not lost or in hiding. Instead, that person needs to walk toward the light.
Yet there is a sense where spiritual things are unseen to those who are in the light. Hebrews 11:1-3 says that “faith is the substance of things hoped for, the evidence of things not seen. For by it the elders obtained a good testimony. By faith we understand that the worlds were framed by the word of God, so that the things which are seen were not made of things which are visible.”
Faith in God produces an inner knowing that what He says is true, with or without any visible evidence. That is, God’s people know what they know about God, not primarily from what we see, but by faith. We walk by faith, not by sight.
For instance, these verses describe my experience regarding creation. When I became a Christian, I thought evolution was more reasonable than God speaking and the world happening. God gifted me with faith to trust Him for forgiveness and eternal life, and as I did, I started to realize that His power is so great that He actually could speak the world into existence. I had no visible evidence for that, and if pressed would have said it went against human reasoning, yet I soon was convinced that God is the Creator, not time and chance.
Like the people described in Romans, at first I’d denied the visible evidence, but when Jesus came into my life, faith showed me that what I had denied was true, and with the gift of faith, I knew it without the evidence. Then God, in grace and mercy, allowed me to see the truth of His creative power not just by faith, but in the evidence that I first rejected.
Seeing is believing? Yes, if I see the handiwork of God in creation, but no if I expect God to suddenly appear so that I can see Him.
Believing is seeing? Yes, if I see God by faith, because after faith became part of my life, I can see much more than I ever imagined was there.