We’re asking you to worship the God of Christ, the God of Muhammad, peace me upon them all. We’re asking you to worship the God who is the Creator of everything.

Muslim means someone who submits and surrenders heir will willingly and sincerely to the will of the one true God.
So Jesus (A.s) was a Muslim because he submitted to God.
All of the things that you see about Christ, that he is a very good Muslim.