Then he can be both. Here is the Bible passages that tend to show he can be visible.<quoted text>of course God would be invisible...in essence, he is spiritual in nature.
And the LORD appeared unto Abram, and said, Unto thy seed will I give this land: and there builded he an altar unto the LORD, who appeared unto him.
And when Abram was ninety years old and nine, the LORD appeared to Abram, and said unto him....
And the Lord appeared unto him in the plains of Mamre.
And the LORD appeared unto him, and said, Go not down into Egypt; dwell in the land which I shall tell thee of.(v.2)
And the LORD appeared unto him the same night, and said, I am the God of Abraham thy father: fear not.(v.24)
And Jacob called the name of the place Peniel: for I have seen God face to face, and my life is preserved.
And God appeared unto Jacob again, when he came out of Padanaram, and blessed him.
And Jacob said unto Joseph, God Almighty appeared unto me at Luz in the land of Canaan.
The LORD God ... appeared unto me, saying, I have surely visited you.
That they may believe that the LORD God ... hath appeared unto thee.
And I appeared unto Abraham, unto Isaac, and unto Jacob....
Then went up Moses and Aaron, Nadab and Abihu, and seventy of the elders of Israel. And they saw the God of Israel ... They saw God, and did eat and drink.
And the Lord spake to Moses face to face, as a man speaketh to his friend.(v.11)
And I will take away my hand, and thou shalt see my backparts.(v.23)
For they have heard that thou Lord art among this people, that thou Lord art seen face to face.
The Lord talked with you face to face in the mount out of the midst of the fire.
And there arose not a prophet since in Israel like unto Moses, whom the Lord knew face to face.
And Manoah said unto his wife, We shall surely die, because we have seen God.
1 Kings 22:19
I saw the Lord sitting on his throne, and all the host of heaven standing by him on his right hand and on his left.
I have heard of thee by the hearing of the ear: but now mine eye seeth thee.
To see thy power and they glory, so as I have seen thee in the sanctuary.
In the year that King Ussiah died, I saw, also, the Lord sitting upon a throne, high and lifted up.(v.1)
For mine eyes have seen the King, the LORD of hosts.(v.5)
And saw ... the appearance of his loins even upward, and from the appearance of his loins even downward....
And I will bring you into the wilderness of the people, and there will I plead with you face to face.
The LORD stood upon a wall made by a plumbline, with a plumbline in his hand.
I saw the Lord standing upon the altar: and he said, smite the lintel of the door, that the posts may shake.
God came from Teman, and the Holy One from mount Paran .... He had horns coming out of his hand.
Take heed that ye despise not one of these little ones; for I say unto you, That in heaven their angels do always behold the face of my Father which is in heaven.