Revelation 4:2

And above the firmament over their heads was the likeness of a throne, in appearance like a sapphire stone; on the likeness of the throne was a likeness with the appearance of a man high above it. Also from the appearance of His waist and upward I saw, as it were, the color of amber with the appearance of fire all around within it; and from the appearance of His waist and downward I saw, as it were, the appearance of fire with brightness all around. Like the appearance of a rainbow in a cloud on a rainy day, so was the appearance of the brightness all around it. This was the appearance of the likeness of the glory of the LORD. So when I saw it, I fell on my face, and I heard a voice of One speaking. (Eze. Eze. 1:26-28)

What John sees is not some immaterial spiritual revelation, but a real material place:

Heaven is a material place. John saw a throne. If the objection is that he was in the Spirit and that it might be a spiritual throne, we would answer that the body of Jesus Christ was raised from the dead and that our Lord said, “Handle me, and see; for a spirit hath not flesh and bones, as ye see me have” (Luke Luke 24:39); and it was that body which ascended into Heaven. There must be a material Heaven or there was no ascension, and if there was no ascension, there was no resurrection, and if there was no resurrection, there is no salvation.²

Notes

¹ God’s throne appears in Rev. Rev. 1:4+; Rev. 3:21+; Rev. 4:2-6+, Rev. 4:9-10+; Rev. 5:1+, Rev. 5:6-7+, Rev. 5:11+, Rev. 5:13+; Rev. 6:16+; Rev. 7:9-11+, Rev. 7:15+, Rev. 7:17+; Rev. 8:3+; Rev. 12:5+; Rev. 13:2+; Rev. 14:3+, Rev. 14:5+; Rev. 16:10+, Rev. 16:17+; Rev. 19:4-5+; Rev. 20:11+; Rev. 21:5+; Rev. 22:1+, Rev. 22:3+.

² Donald Grey Barnhouse, Revelation (Grand Rapids, MI: Zondervan Publishing House, 1971), 89.