John Chrysostom
Although there was a tabernacle, there were not yet sacrifices. That there were none the prophet says clearly: "Did you offer sacrifices and grain offerings to Me?" (Amos 5:25).
There was the tabernacle "of witness," but it brought them no benefit, and they were perishing. Likewise, signs brought them no benefit, either before or afterward.
But why, someone will say, is the tabernacle called "the tabernacle of witness" (μαρτυρίου)? Because it existed so that they might have God as witness (μάρτυρα). For this alone it existed.
"According to the pattern shown you on the mountain" (Ex 25:40). Therefore its pattern was shown on the mountain. It was carried in the wilderness and did not stand in one place.
It is called the tabernacle of witness for no other reason than the wonders and commandments. Yet neither it nor they had a temple. And since its very pattern was shown, it was therefore shown by the angel himself.