Dead men, unfortunately, are also blind men.
Man once had life and spiritual connection to God when he was created up until he sinned. But in the day he sinned he died in his soul existence. To give an illustration of what it means to be connected to God---it is like a city connected to a power source. As long as there's a connection there is light and life. But the day man sinned, God disconnected man from the power source. Like a city experiencing a blackout. Man's soul became dark and lifeless.
Throughout time God's salvation program has served to restore the connection (Psalm 23 says, He restoreth my soul) lost due to the fall into sin. The individual that God saves is energized once again with spiritual light and life. His soul is illuminated to spiritual things. It's like the blackout is over and all the city's lights come back on. But those that are not saved remain in their fallen disconnected state of darkness and death. As though they live in a city perpetually experiencing a blackout.
The way this works out between the two different types of people is that the child of God has light to see with; but the unregenerate individual has no light. An unsaved man is viewing things through a darkened prism. In his spiritually darkened condition a person may say there is no God, or that the Bible is a work of fiction. These statements go along with the individual's personal experience of seeing nothing and encountering nothing in the spiritual realm. God and His Word are shrouded in darkness to them.
A child of God though has had a completely different experience. He also has spent some period of time in the darkness. So he knows what that is like. But through no doing of his own, and completely by God's grace, the lights have come on in his spirit. The soul has been restored. The child of God has been given the ability to see the reality of spiritual existence of God and His invisible kingdom.
2 Corinthians 4:6 For God, who commanded the light to shine out of darkness, hath shined in our hearts, to give the light of the knowledge of the glory of God in the face of Jesus Christ. This 'light' reveals things we never could see before.
John 1:4 In him was life; and the life was the light of men.
5 And the light shineth in darkness; and the darkness comprehended it not.
This was the experience of the man Moses:
Hebrews 11:24 By faith Moses, when he was come to years, refused to be called the son of Pharaoh's daughter;
25 Choosing rather to suffer affliction with the people of God, than to enjoy the pleasures of sin for a season;
26 Esteeming the reproach of Christ greater riches than the treasures in Egypt: for he had respect unto the recompence of the reward.
27 By faith he forsook Egypt, not fearing the wrath of the king: for he endured, as seeing him who is invisible.
Moses saw him that was invisible. How is it possible to see One that is invisible? The answer is through the spiritual sight of faith that God gives to His people:
Hebrews 11:1 Now faith is the substance of things hoped for, the evidence of things not seen.
Faith is the evidence of things not seen. Evidence is that which proves something. Faith proves the existence of the invisible (spiritual) kingdom of God and of the Spirit Being God Himself.
You, and others say, no, Moses didn't see anyone. And neither does anyone else that says there is a God. You insist we cannot see invisible things with eyes of faith. That's your right to say what you wish. But the fact is that your lack of sight in the spiritual realm does not mean everyone else lacks sight in the spiritual realm. The testimony of God's true people is always, as the hymn Amazing Grace declares, "I was blind, but now I see."
John 9:39 And Jesus said, For judgment I am come into this world, that they which see not might see; and that they which see might be made blind.