The original:
"Caedite eos. Novit enim Dominus qui sunt eius."
or
"Slay them all. God will know his own"
was used in the crusades.
My understanding is that a French General, when asked by his lieutenants how to separate the Muslims from the Christians during the conquest of a city, were told , kill them all for God will know his own.
That looks like a tagline.