On John5:18.

  Depending on whom one asks this verse is supposed to be a defeater for Christians who accept the God and Father of Jesus Christ as the one true God:

Braggadocio or substance?Well let's have a look:John5:18NASB"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."
The first thing you'll notice about those who misuse this verse to promote trinitarian or modalist notions is that they invariably focus on the second charge and not the first thus bringing their competence if not their sincerity into question.Manifestly both charges are from the same source and the fact that they are parallelled indicates that they are  both either equally improper or proper depending on ones argument.
 Usually our trinitarian or modalist friends would insists that charge no.2 is John's opinion if we accept this line of logic we are compelled to further conclude that charge number one is also John's opinion.So did the apostle John really opine that his master failed to practice what he preached in breaking the Sabbath see Matthew5:19 or that claiming Jehovah as Father was blasphemous,An opinion that would render John himself guilty of blasphemy 1John3:1,2 later on at John8:41 the Jews also claim Jehovah God as their father were they thus making themselves equal to God.
  Obviously it was the Jewish religious leaders in their zeal for legalism who falsely concluded that Jesus kindly healing of this son of Abraham on the most appropriate day for such charity amounted to a violation of the sabbath and it was the same group who with equally faulty reasoning concluded that Jesus acknowledgment of almighty God as the source of the power manifested through him and that God would not have made such power available to him if he was not favored by him as a Father would favor a son meant that he was trying to steal God's thunder so to speak.
  While we are on the subject of opinions what was Jesus' opinion on the matter,we need not speculate he makes it quite clear in the following verse "Therefore Jesus answered and was saying to them, “Truly, truly, I say to you, the Son can do nothing of Himself, unless it is something He sees the Father doing; for whatever the Father does, these things the Son also does in like manner." Clearly Jesus was not of the opinion that his being God's son made him equal to God.