Was Jesus Elohim and 'the Jewish God' Yahweh?

Even if "the letter killeth, yet the Spirit giveth life" and both belong to Him who says: "I kill, and I make alive; I wound, and I heal." We have already made good the Creator's claim to this twofold character of judgment and goodness ----"killing in the letter" through the law, and "quickening in the Spirit" through the Gospel. Now these attributes, however different they be, cannot possibly make two gods; for they have already (in the prevenient dispensation of the Old Testament) been found to meet in One. [Tertullian, Adv Marc 5.11.4]