Jesus is quoting from Psa 82:6-7 "I have said, Ye are gods; and all of you are children of the most High. But ye shall die like men, and fall like one of the princes." Why is he quoting that? The Jews said He blasphemed by saying "I am the Son of God," so He is pointing out to them that all who truly receive the word of God are sons of God, but He is the Son of God in a much higher & truer sense.
Remember that John 1:12 says "But as many as received him, to them gave he power to become the sons of God, even to them that believe on his name:" When we believe, we receive the power & right to become sons of God, but we have not actually used this right & power and have not actually become sons of God until baptism, as Paul says in Galatians 3:26-27 "For you are all the children of God by faith in Christ Jesus, because as many of you as have been baptized into Christ have put on Christ." By faith we have the right to become sons of God, and by baptism we use that right and actually do become such.
Now, Jesus is not a son of God by adoption, as are Christians. He is and always has been the only begotten Son of God, begotten of the Father before all works, "He is the image of the invisible God, the firstborn over all creation." (Col 1:15)
Therefore, then, Jesus asks the Jews "If He called them gods, to whom the word of God came (and the Scripture cannot be broken), do you say of Him whom the Father sanctified and sent into the world, 'You are blaspheming,' because I said, 'I am the Son of God'?" (John 10:35-36) In otherwords, if you yourselves could become sons of God by submitting to His word, why do you accuse me of blashpemy when I say "I am the Son of God" seeing I always have been and was consecrated and sent down to earth out of heaven itself? If even you could be called sons of God, by adoption, certainly I may also since I am the only begotten Son of God, begotten of the Father before all worlds.
