There are some, who think Jn 5:19 proves that Jesus (God Incarnate, they say) was impeccable (not able to sin). Robert M. Bowman asserts that we should understand 5:19 to say, "I would never act independenty of my Father." Or it appears to be teaching that the Lord would never sin against his Father and that he could not sin.
Jn 5:19 is a response to two accusations: (1) Jesus broke the Sabbath; (2) the Son was calling God his Father, seemingly making himself equal to God. In reply, the Lord does not say that "he would never act independently of the Father." Rather, he utters the words, Ἀμὴν ἀμὴν λέγω ὑμῖν, οὐ δύναται ὁ υἱὸς ποιεῖν ἀφ' ἑαυτοῦ οὐδὲν ἂν μή τι βλέπῃ τὸν πατέρα ποιοῦντα· ἃ γὰρ ἂν ἐκεῖνος ποιῇ, ταῦτα καὶ ὁ υἱὸς ὁμοίως ποιεῖ.
Paul N. Anderson (The Christology of the Fourth Gospel, 3, 267) observes that Jesus is asserting that he "can do nothing on his own authority" and is "totally dependent" on his Father. For Anderson, Jn 5:19 is a Johannine "subordinationist" passage. In other words, Christ is evidently stating that he does not have the ability (οὐ δύναται) or authority to act on his own initiative. He is not suggesting that he would never act on his own. Such an interpretation of 5:19 is much too strong and it misrepresents the pragmatic meaning of Jesus' words. Moreover, when the Lord insists that he does what he beholds the Father doing, the relative pronoun ἃ ("whatsoever") is delimited by the context. In particular, the things Jesus' Father does in this case regard sustaining the creation. Jn 5:17 supports this point by showing that God's ability to split seas or know all things is not the issue. Jn 5:19 is not claiming that Christ does exactly what the Father does in all respects. Robertson also offers this comment:
"Can do nothing by himself (οὐ δύναται ὁ υἱὸς ποιεῖν ἀφ' ἑαυτοῦ οὐδὲν). True in a sense of every man, but in a much deeper sense of Christ because of the intimate relation between him and the Father. See this same point in Joh_5:30; Joh_7:28; Joh_8:28; Joh_14:10. Jesus had already made it in Joh_5:17. Now he repeats and defends it" (Word Pictures).
If the utterance is true (in a sense) of all humans, then how could the text prove that Jesus Christ was impeccable? The quote above certainly indicates that Robertson does not think Christ's declaration means that he could not sin, even if the famed grammarian believed in Christ's impeccability.
In conclusion, I agree with Charles Hodge (Systematic Theology 2:457) who argued that the temptations of Christ were not genuine and were ineffectual, if he was impeccable (incapable of sinning). I also believe that a free moral agent always maintains the ability to perform A or to refrain from performing A. Christ was a free moral agent: he could choose to act independently of the Father, if he had so desired. However, he would then have been powerless, and incapable of healing anyone or doing any good portentous works (Acts 2:22 NWT):
Ἀμὴν ἀμὴν λέγω ὑμῖν, οὐ δύναται ὁ υἱὸς ποιεῖν ἀφ' ἑαυτοῦ οὐδὲν