Tertullian, Against Marcion 8

The Marcionites open their case with a flourish: they parade a 'new God' as if we should be embarrassed by the old one. Children puff themselves up over new shoes, too, but an old schoolmaster soon makes them pay for their empty pride. So they announce a new God—unknown, unheard of in the old world, the old age, under the old God—whom no one knew, not even ignorance itself, as ancient, until a certain Jesus Christ revealed him. And he did it in old names, yet made them new. No one else had done it before. I thank them for this boast; it is the greatest help I could ask for in proving their heresy—the claim of a new divinity. That is the kind of novelty that even spawned new gods for the pagans, each consecrated with a brand-new, ever-new title. What is a new god but a false one? Not even Saturn’s vast antiquity makes him a god today, because novelty once produced him, back when he was first consecrated. Living, genuine divinity is measured not by novelty or antiquity, but by its own truth. Eternity has no time; it is all time. What it does, it cannot undergo. It has no age, because it cannot be born. If God is old, he will cease to be; if he is new, he never was. Novelty testifies to a beginning; antiquity threatens an end. But God is as far removed from beginning and end as he is from time itself—the arbiter and measurer of both.