In Isaiah 42:4 we read of a most glorious truth about our blessed Lord and Saviour Jesus Christ, "He shall not fail nor be discouraged." As God’s Servant and Christ He came into this world to do the will of God. He said, "My meat is to do the will of him that sent me, and to finish his work" (Jn. 4:24). Of this we can be certain, that everything the Father sent the Son to accomplish, He fulfilled it to the exact will, purpose and delight of God Almighty. It is recorded in verse 21 of this same chapter, "The Lord is well pleased for his righteousness’ sake; he will magnify the law, and make it honourable.." The Lord Jesus was the delight of the Father in eternity (Prov. 8: 22-30). And when He was manifested in the flesh in time, Jesus Christ pleased the Father, "This is my beloved Son, in whom I am well pleased" (Matt. 3:17).
The exact opposite is true of man, from the beginning he has been a failure. Adam, even in his perfect environment that God had placed him in failed. All of Adam’s race has inherited from the first man, a fallen and depraved nature that cannot produce anything before God but failure and sin (Rom. 5:12). God has said of us, "Verily every man at his best state is altogether vanity" (Psa. 39:5); "For there is not a just man upon the earth that doeth good, and sinneth not" (Eccl. 7:20).
This should give every sinner great incentive and inspiration to look to the Christ of God that cannot fail and trust Him for all things in salvation. The sinner needs righteousness, Jesus Christ did not fail to produce righteousness for us (Rom. 10:4). We need redemption from all our sin, Jesus Christ with His own blood redeemed us from the curse of the law (Gal. 3:13; Heb. 9:12). We need salvation, He saved His people with an everlasting salvation (Isa. 45:17). We need to be justified, Jesus Christ justified us through His blood (Rom.5:9). In every aspect of our salvation, Jesus Christ as our Mediator and Substitute did not fail to honour God’s holy justice in securing our salvation.
Therefore, we can rightly conclude, that those for whom Jesus Christ lived and died as Representative and Advocate cannot perish (John 6:37-40). Because He lives we live (John 14:19). Because He did not fail as our Substitute to please and satisfy God (Psa. 85:10), we did not fail being in Him (Gal. 2:20). This causes the believer to bow in humble adoration and say, Lord, how great Thou art. We give thanks unto God that did not leave us to our own miserable failures, but revealed unto us, the Lord Jesus Christ who did not and will never fail. He performed all things in salvation for us (Psa. 57:2).