I looked it up to see if there was context to add, and the line immediately preceding the one the cardinals are quoting (Ephesians 6) is, "Put on the whole armour of God, that ye may be able to stand against the wiles of the devil." Look how we lead into this beat. Someone at Ubi had fun with this:

So on the way out of the Vatican with Mario in AC: Brotherhood, you'll pass some cardinals in prayer. "For we wrestle not against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this world, against spiritual wickedness in high places."