Look closely at our Lord's right hand in this mosaic from Hagia Sophia (central figure).

Theodoret (A.D. 393–457), bishop of Cyrrhus, Syria, gave the following instruction:

This is how to bless someone with your hand and make the sign of the cross over them. Hold three fingers, as equals, together, to represent the Trinity: God the Father, God the Son, and God the Holy Ghost. These are not three gods, but one God in Trinity. The names are separate, but the divinity one. The Father was never incarnate; the Son incarnate, but not created; the Holy Ghost neither incarnate nor created, but issued from the Godhead: three in a single divinity. Divinity is one force and has one honor. They receive on obeisance from all creation, both angels and people. Thus the decree for these three fingers. You should hold the other two fingers slightly bent, not completely straight. This is because these represent the dual nature of Christ, divine and human. God in His divinity, and human in His incarnation, yet perfect in both. The upper finger represents divinity, and the lower humanity; this way salvation goes from the higher finger to the lower. So is the bending of the fingers interpreted, for the worship of Heaven comes down for our salvation. This is how you must cross yourselves and give a blessing, as the holy fathers have commanded.

In Hagia Sophia and on Patmos, where John received The Revelation, we found ancient art and mosaics with characters holding their right hand in a variation of this instruction that's basically a way of depicting someone as an orthodox Christian. Do you see the irony of destroying art of crosses but leaving a picture of Christ testifying to the Trinity and His dual nature?