Tertullian

Their truth may be inferred from their agreement with the apostle's own profession, how "to the Jews he became as a Jew, that he might gain the Jews, and to them that were under the law, as under the law,"-and so here with respect to those who come in secretly,-"and lastly, how he became all things to all men, that he might gain all." Now, inasmuch as the circumstances require such an interpretation as this, no one will refuse to admit that Paul preached that God and that Christ whose law he was excluding all the while, however much he allowed it, owing to the times, but which he would have had summarily to abolish if he had published a new god.