Question: Based upon Gal:2:20 ("I live by the faith of the Son of God"), some teach that Christ had to have faith in God like any of us—that He did miracles by faith in God, was the perfect example of the operation of the gifts of the Holy Spirit—and thus we can do the same—and that it is by the "faith of the Son of God" that we live the Christian life. But what faith did the Lord have, or need to have? As God in the flesh, He was very God and also very man. As a man, did He have to have faith in Himself as God? When He did "...the works which none other man did...," was this by faith in God, or by His power as God? Please give me your thoughts on this subject.
Response: As you noted, those who teach this doctrine derive it from the KJV's "by the faith of the Son of God." This is not a wrong translation. It is simply old English and the KJV's peculiar way of saying "by faith in." Thus, the New King James renders it "faith in," as does every other translation I could locate. English words continually change their meaning, so it is not surprising that the KJV could be misunderstood in some places.
The KJV's old English sometimes means the opposite of that word's meaning today. For example, "He who now letteth will let" (2 Thes:2:7) today means to "allow." But it comes from the Greek word, katecho, which literally means "to hold down." In today's English it would be, "he who now restrains." So it is rendered in the New King James and elsewhere.
Thus, this doctrine that we live by "the faith of Christ" is based upon a mistaken understanding of the old English, which would be quickly cleared up by consulting other translations. "The Comparative Concordance" of Strong's Exhaustive Concordance shows, on p. 145, that this clarification was made in the revised edition of the KJV—not only in Gal:2:20 but at 3:22 and elsewhere. I am not endorsing the revision of the Authorized Version, largely controlled by modernists such as Westcott and Hort, who were intent upon destroying the truth. In relation to Gal:2:20, however, no such motive could be ascribed for changing "faith of Christ" into "faith in Christ." Indeed, I cannot imagine what "living by the faith of Christ" could possibly mean!
As you point out, the corollary of this teaching is the equally erroneous belief that Christ, while on this earth, lived by faith as an example for us. On the contrary, He told us to "have faith in God" (Mk 11:22)—but He is God and doesn't live by faith in Himself. Nowhere do I find that Christ lived by faith. Yes, He said, "the Son can do nothing of himself, but what he seeth the Father do...I can of mine own self do nothing...but the will of the Father which hath sent me...the words that I speak, I speak not of myself: but the Father that dwelleth in me, he doeth the works" (Jn:5:19, 30; 14:10, etc.). But this is not something applicable to the Son only in His incarnation as a man. It is the consequence of His being eternally one with the Father and of the unity within the Godhead. Likewise, the Holy Spirit does nothing on His own (Jn:16:13).
Christ did miracles by His intrinsic power as God. When He told Nathanael that He had seen him under the fig tree where he was sitting when Philip called him, Nathanael declared, "Rabbi, thou art the Son of God" (Jn:1:49)! Jesus didn't say, "You can't draw that conclusion from the power I display; I simply do miracles by faith in God like any believer can." So this teaching demeans Jesus and refuses to recognize His many declarations of His deity, which the rabbis understood and for which they crucified Him.
Is Christ living by faith in heaven today and somehow His faith is imparted to us? Of course not. Is it His continuing faith since returning to heaven that sustains us? If so, then how do we account for the many sins and failures of Christians? He is God and shares the throne of the universe with the Father, of whom He said, "I and my Father are one" (Jn:10:30). How would this alleged "faith of Christ" express itself in our lives? It surely couldn't be automatic. Must we have faith in "the faith of Christ" rather than in Him, as Scripture exhorts us? Peter refers to "the trial of your faith" (1 Pt 1:7). Jesus tells us to "have faith in God" (Mk 11:22). We are told repeatedly that our faith must be in Christ and in God. We must believe the gospel.
Furthermore, Christ often used the phrase, "thy faith" in speaking to those who put their trust in Him. Sinners are told to "believe on the Lord Jesus Christ" (Jn:3:16; Acts:16:31, etc.). Paul everywhere preached "faith toward [or in] our Lord Jesus Christ" (Acts:20:21). I cannot find anywhere in Scripture where we are told to have faith in the faith of Christ. This is simply a misunderstanding of old English and is an unfortunate embarrassment to those who preach it.