For those who have expressed that because Jesus is referred to as the "Son of God" and the "Son of man" He was not therefore God I offer this short rejoinder.
"Many other signs therefore Jesus also performed in the presence of the disciples, which are not written in this book; but these have been written that you may believe that Jesus is the Christ, the Son of God; and that believing you may have life in His name” (Jn. 20.30-31). The apostle John wrote his gospel with the expressed intention of convincing his readers to believe in Jesus Christ. Part of this belief is that Jesus Christ is the Son of God. On the phrase “Son of God” James Buswell writes: “Christ is called ‘Son of God’ scores of times in the New Testament. I take the key passage on this subject to be John 5.18, On this account rather the Judeans sought to kill him because he called himself equal with God (Jn. 5.18). In Jewish usage the term ‘son of . . .’ did not generally imply any subordination, but rather equality and identity of nature. Thus Bar Kokba, who led the Jewish revolt 132-135 A. D. in the reign of Hadrian, was called by a name which means ‘Son of the star.’ It is supposed that he took this name to identify himself as the very star predicted in Numbers 24:17. The name Son of Consolation (Acts 4.36) doubtless means ‘The Consoler.’ ‘Sons of Thunder’ (Mark 3.17) probably means ‘Thunderous Men.’ ‘Son of Man’ especially as applied to Christ in Daniel 7:13 and constantly in the New Testament, essentially means ‘The Representative of Man.’ Thus for Christ to say, ‘I am the Son of God’ (Jn. 10.36) was understood by His contemporaries as identifying Himself as God, equal with the Father, in an unqualified sense” (Systematic Theology, p. 105).
The expression “Son of God” is used in the NT as a description of Christ’s deity. For example, in Jn. 5.17-18 Jesus says, “My Father is working until now and I Myself am working. For this cause therefore the Jews were seeking all the more to kill Him, because He not only was breaking the Sabbath but also was calling God His own Father, making Himself equal with God.” The Jews understood that to be God’s Son was to be equal to God. Notice Jesus does not correct their reasoning, but presents a stunning defense of His claim in verses 19-47. Likewise, in Jn. 10.30-39 there occurs a similar situation where the Jews to whom Jesus speaks with understand His claim to be the Son of God as a direct claim to deity, and, as before, Jesus does not try to correct their reasoning, but again presents a defense of His claim."
Context of John 5: 9b-18
Now it was the Sabbath on that day. 10 So the Jews were saying to the man who was cured, “It is the Sabbath, and it is not permissible for you to carry your pallet.” 11 But he answered them, “He who made me well was the one who said to me, ‘Pick up your pallet and walk.’” 12 They asked him, “Who is the man who said to you, ‘Pick up your pallet and walk’?” 13 But the man who was healed did not know who it was, for Jesus had slipped away while there was a crowd in that place. 14 Afterward Jesus *found him in the temple and said to him, “Behold, you have become well; do not sin anymore, so that nothing worse happens to you.” 15 The man went away, and told the Jews that it was Jesus who had made him well. 16 For this reason the Jews were persecuting Jesus, because He was doing these things on the Sabbath. 17 But He answered them, “My Father is working until now, and I Myself am working.” 18 For this reason therefore the Jews were seeking all the more to kill Him, because He not only was breaking the Sabbath, but also was calling God His own Father, making Himself equal with God.
IMPORTANCE OF THE DEITY OF CHRIST
"On this subject Boettner has well summarized: “The Deity of Christ is thus taught in Scripture so explicitly and repeatedly that the question is settled for all those who accept the Bible as the word of God. There can be no question but that Jesus Himself as He is portrayed in the New Testament records presented Himself as God incarnate. Nor is there any doubt but that the writers of the New Testament personally held this same high estimate of Him and worshiped Him as God, or that the Church in all ages in all its great branches, whether Roman Catholic, Greek Catholic, Lutheran, Reformed, Presbyterian, Episcopal, Methodist, Baptist, or Congregational, as its faith has been expressed through its creeds and hymns and devotional writings, has likewise conceived of Him. And throughout the ages the great mass of those who have read the New Testament have come to the same conclusion.
In view of this great mass of evidence we are completely unable to understand how any fair-minded person can rise up and say, as do the Unitarians and Modernists, that Christ was not Deity, or that He did not claim Deity. In fact, we must go farther and say that such opposition appears to be based on nothing other than blind opposition and a determination not to accept that evidence no matter how clear and strong it may be. Any denial of the Deity of Christ, together with the implication that He was merely a great teacher or prophet, gives one a viewpoint other than that from which the Scriptures are written and makes it impossible for him to comprehend the system of truth that is revealed in Scripture. Such denial throws one out of harmony with the great Source of wisdom and truth, which is God, and causes him to attempt to explain intellectually that which can only be discerned spiritually.
The pre-eminent importance of the doctrine of the Deity of Christ in the Christian system is shown by the fact that this is the test by which we are to distinguish between true and false prophets, between spirits which are of God and spirits which are not of God. The Apostle John, after giving the warning, ‘Beloved, believe not every spirit, but prove the spirits, whether they are of God; because many false prophets are gone out into the world,’ adds these words: ‘Hereby know ye the Spirit of God: every spirit that confesseth that Jesus Christ is come in the flesh is of God; every spirit that confesseth not Jesus is not of God, and this is the spirit of the antichrist, whereof we have heard that it cometh, and now it is in the world already,’ 1 John 4:1-3. Here we are plainly told that every one who acknowledges that Christ has come in the flesh is of God, and that every one who denies the Deity of Christ is antichrist. Regardless of how eloquent the speaker may be, how pleasing or magnetic his personality, how widespread his in influence, or even how sincere his motives, the prophet or preacher or teacher who denies the Deity of Christ is branded in Scripture as a false prophet or preacher or teacher. And to the same effect Paul says: ‘No man speaking in the Spirit of God saith, Jesus is anathema; and no man can say, Jesus is Lord, but in the Holy Spirit,’1 Cor. 12:3. Here Paul declares that only by the spiritual insight which the Holy Spirit gives as He regenerates a soul can that soul form a true judgment of the Deity of Christ. No one recognizes Christ as Lord and as his Lord unless he has been born again. The man who looks at Jesus only with his own unenlightened eyes sees in Him only a man, perhaps a great man with many lofty principles and ideals, yet a man who has claimed too much for Himself and who has committed blasphemy by calling himself the Son of God. But when the Holy Spirit comes into his life, renewing and enlightening him spiritually, he then sees himself a guilty, condemned sinner who merits nothing but God’s wrath and punishment. But he is also given to see, by the eye of faith, that Jesus is the Son of God, that He lived on this earth, that He was crucified for the sins of His people, that He arose from the grave, and that He now reigns from heaven. Never does a mortal man see the Lord Jesus thus, and never does he accept Him as his Lord, unless it is given him by the Holy Spirit. Thus Paul says that no person can acknowledge Jesus as Lord unless he has been enlightened by the Holy Spirit. And, incidentally, in these words he also tells us that the person who does thus acknowledge Jesus as Lord has been regenerated and is therefore assured of salvation." The Deity of Christ by Michael Bremmer