Tertullian, Against Marcion 34
Christ forbids divorce: "Anyone who divorces his wife and marries another commits adultery, and the man who marries a divorced woman is equally an adulterer." He makes remarriage after divorce unlawful, thereby forbidding divorce itself. Moses, however, permits divorce in Deuteronomy: if a man takes a wife, lives with her, then finds no favor in her because he discovers something indecent, he writes a certificate of divorce, hands it to her, and sends her away (Deut 24:1–4). You see the clash between the Law and the Gospel, between Moses and Christ? Of course you do. You haven't accepted that Gospel—the same truth, the same Christ—in which, while forbidding divorce, he settles his own question: "Moses, because of your hard hearts, allowed you to divorce your wives, but from the beginning it was not so. The Creator made them male and female, and said, ‘The two shall become one flesh.’ So what God has joined together, let no one separate" (Matt 19:8–6; Gen 2:24). By that answer he both shields Moses' statute as his own and upholds the Creator's institution as Christ's own.
Now, to convict you on the grounds you actually accept, I'll meet you on your own turf—as if my Christ were yours. Doesn't he, while forbidding divorce, still share the mind of the One who joined male and female, and therefore *excuse* Moses' law rather than destroy it? But look: if your Christ teaches the opposite of Moses and the Creator, then he's mine—unless I can prove the opposite. I say he imposed the ban *conditionally*: "If a man divorces his wife *in order to marry another*, he commits adultery; and whoever marries a woman divorced *on that ground* is likewise an adulterer, because the original marriage was never lawfully dissolved. As long as that marriage stands, remarrying is adultery." So if the prohibition is conditional, it's not total; and what isn't totally forbidden is permitted in cases where the reason for the ban disappears.
Latin
(Sed Christus diuortium inhibet dicens: qui dimiserit uxorem suam et aliam duxerit, adulterium committet, (et) qui dimissam a uiro duxerit, aeque adulter est, - ut sic quoque prohibeat diuortium, inlicitum facit repudiatae matrimonium — Moyses uero permittit repudium in Deuteronomio: si sumserit quis uxorem et habitauerit cum ea, et euenerit non inuenire eam apud eum gratiam, eo quod inuentum sit in illa impudicum negotium, scribet libellum repudii et dabit in manu eius et dimittet illam de domo sua. uides diuersitatem legis et euangelii, Moysi et Christi'? plane. non enim recepisti illud quoque euangelium eiusdem ueritatis et eiusdem Christi, in quo prohibens diuortium propriam quaestionem eius absoluit: Moyses propter duritiam cordis uestri praecepit libellum repudii dare; a primordio autem non fuit sic; quia scilicet qui marem et feminam fecerat, erunt duo, dixerat, in carne una; quod deus itaque iunxit, homo (non) disiunxerit. hoc enim responso et Moysi constitutionem protexit, ut sui, et creatoris institutionem direxit, ut Christus ipsius. sed quatenus ex his reuincendus es, quae recepisti, sic tibi occurram, ac si meus Christus (tuus:) nonne et ipse prohibens diuortium et parem tamen gestans eius, qui marem et feminam iunxit, excusauerit potius quam destruxerit Moysi constitutionem? sed ecce sic tuus sit iste Christus contrarium docens Moysi et creatori, ut, si non contrarium ostendero, meus sit. dico enim illum condicionaliter nunc fecisse diuortii prohibitionem, si ideo quis dimittat uxoiem, ut aliam ducat: qui dimiserit, inquit, uxorem et aliam duxerit, adulterium commisit, et qui a marito dimissam duxerit aeque adulter est, ex eadem utique causa dimissam, qua non licet dimitti, ut alia ducatur; inlicite enim dimissam pro indimissa ducens adulter est. manet enim matrimonium quod non rite diremptum est; manente (autem) matrimonio nubere adulterium est. ita si condicionaliter prohibuit dimittere uxorem, non in totum prohibuit, et quod non prohibuit in totum, permisit alias, ubi causa cessat, ob quam prohibuit;