I am Christ.—Literally, I am He. The word 'Christ' is a necessary inference from the context.

The Venerable Bede: Because the Lord, when some were praising the buildings of the temple, had clearly answered that all these …

The first word of the discourse proper is “Watch out” (GK 1063), a word that recurs throughout the passage (vv.9, 23, 33, where it is translated as…

For many shall come in my name
Taking upon them the name of the Me iah: saying,

I am [Christ]