Is God Jesus or Jesus is God?

Does the verse 5:17 mean as if Christians believe Christ is Only God or Godhead is confined to Jesus by saying God is Messiah? I also want to copy this from a Christian missionary: "Fifth, the Quran also distorts Christian beliefs regarding the Person of Christ when it accuses Christians of saying that God, or Allah, is the Christ. The historic Christian position is that Jesus is God, which is not the same as saying that God is Jesus. The former implies that Christ is fully God in essence; that he has the entire essential attributes of Deity and is all that God is, whereas the latter suggests that Christ is the only one that is God. In other words, saying that God is Jesus means that the entire Godhead is instantiated in Christ alone to the exclusion of the Father and the Holy Spirit, or that the Father, Son and Holy Spirit are nothing more than manifestations of a single Divine Person. This latter understanding would imply that Christ is all three manifestations, which is a form of an ancient heresy known as Sabellianism which was condemned by the early Church, why would it still be the problem for the Quran ."