God is invisible (1 Timothy 1:17) and no one has ever seen God, though Jesus has made known to us God as He really is (John 1:18).
What about the theophanies of the Old Testament such as Genesis 32:28-30, Exodus 24:9-11, and Isaiah 6:1 is which people did see God? These were manifestations in which God showed Himself in a physical form but that form is not the fullness of what God is actually like.
The invisibility of God is why science can never lead us to God. By definition science can only investigate and describe what it can observe. God is not such a specimen, He is not even a phenomenon that can be analyzed. So far as science is concerned, God cannot be measured, so God cannot exist. It is only through the person of Jesus Christ that we can know God. (For more on this listen to The Unseen God by Dick Lucas).
There are several reasons why we cannot see God. The obvious one is because He is spirit (John 4:24) and we cannot see spirit beings with our physical eyes. Another reason is that He is holy and we are sinners. He dwells in unapproachable light (1 Timothy 6:16), we dwell in places darkened by sin. It is therefore merciful of God to have veiled Himself so that we are not destroyed by seeing His glory in our sinful state.
A day is coming when that veil will be taken away and every eye will see Christ (Revelation 1:7) and be terrified. Yet for those who belong to Him it will be glorious to see His face (Revelation 22:4). As Wayne Grudem writes:
“When we realize that God is the perfection of all that we long for or desire, that he is the summation of everything beautiful or desirable, then we realize that the greatest joy of the life to come will be that we “shall see his face”.”
From Wayne Grudem, Systematic Theology p189.