Was Justin Martyr a Unitarian? Or did he deny that Christ was God?
Neither. In refuting the charge that Christians were atheists, Justin explains that Christians are not atheists but worship and adore the Father, the Son and the Spirit. (First Apology, chap. 6)
Throughout much of his Dialogue with Trypho the Jew, Justin argues that Christ is God, beginning especially about chapters 36-38, and continuing with chapters 48, 55-129.