Further reflections on the nominative in Revelation 1:4: “from he who is, was, comes.”
As Michael Wilcock and others point out, John’s grammatical “error” makes a theological point: God is not subject to declension. He is always subject, never object.
Remarkably, though, John does change tense: He is, and He was. We have no future tense, but instead a participle of erchomai , which stands in for the future.
God doesn’t decline. But He does conjugate.