Antimatter is simply another form of the kind of thing out of which we're all made, which is regular matter. That's basic and standard and by no means suspicious or threatening.

God, if he or she is a God, is above all kinds of matter. If they weren't, they wouldn't be God. God created all matter.

So, to think that God is identified with one kind of matter alone isn't correct. God is above not only all kinds of matter but all kinds of energy. (You've heard of dark energy, haven't you?)

Watch out what they tell you. Sometimes it can be wrong!