“We saw that the ascension of the Lord is grounded on His descent from heaven, and that both flow from and belong to His person as the Son of man that is in heaven. But the Lord follows this up by setting out the mighty work He came to do for sinners, that they might have eternal life—by grace, indeed, but on the footing of divine righteousness.
“And even as Moses lifted up the serpent of brass in the wilderness, so must the Son of man be lifted up; that every one that believeth on him should not perish, but have eternal life. For God so loved the world that he gave his only-begotten Son, that every one that believeth on him should not perish, but have life eternal.” (Ver. 14-16.)
The new birth had been already insisted on for man to see or enter the kingdom of God. But so is the cross also a necessity, if guilty man was to receive pardon from God whilst living to Him. They are alike indispensable. Compare 1 John 4:9, 109In this was manifested the love of God toward us, because that God sent his only begotten Son into the world, that we might live through him. 10Herein is love, not that we loved God, but that he loved us, and sent his Son to be the propitiation for our sins. (1 John 4:9‑10). And Christ as He alone could be, so was sent a propitiation for our sins. The Lord here illustrates the latter truth by the well-known scene in the wilderness, where God directed Moses, in his distress for the guilty Israelites bitten by the fiery serpents and dying in all quarters, to set a serpent of brass on a pole, that whoever looked might live. It was the figure of Himself, who knew no sin, for us made sin, identified in divine dealing with the consequences of our evil in judgment on the cross. Impossible that sin could otherwise be expiated adequately. It must be by God's judging it in One capable of bearing what it deserved at His hands; and it must be in man, in the Son of man, to be available for man. Yet, had it been any other than Jesus, it had been offensive to God, and not efficacious for man; for He only was the Holy One, and in no offering was there more jealous care that it should be without blemish. “It is most holy,” says the law of the sin-offering. All other men were shapen in iniquity, and in sin conceived, in Him only of woman born is no sin, not only no sin committed, but no sin in Him. Therefore was a body prepared Him as for no one else, when the Holy Ghost came on the Virgin Mary, and the power of the Highest overshadowed her. Therefore also that Holy Thing which was born was called the Son of God; not only the Son of God before He was sent of the Father, but, when in grace the Word thus became flesh, perfect man, yet not the less truly God. For there was none other way, if the desperate case of man was to be remedied before God. It could only be righteously through atonement; and the Son of man was the only fitting victim. For blood of bulls and goats is incapable of taking away sins, however instructive such sacrifices might be beforehand of man's need and of God's way. “Wherefore, when he cometh into the world, he saith, Sacrifice and offering thou wouldest not, but a body didst thou prepare me. In burnt-offerings and sacrifices for sin thou hadst no pleasure. Then said I, Lo I am come (in the volume of the book it is written of me) to do thy will, O God.”
Thus did the man Christ Jesus, Son of God withal, yea, God over all blessed forever, deign to suffer once for sins, just for unjust, that He might bring us to God. Only so could it be, for God could not make light of sin, however surely He can and does pardon sinners; but even He could not pardon consistently with Himself or His word, or the creature's real blessing, but through blood of the cross. And therefore did the Lord say here to Nicodemus, who knew the law, if he had little known the prophets, “As Moses lifted up the serpent in the wilderness, even so must the Son of man be lifted up.” Thus did He redeem out of the curse of the law, having become a curse for us. It is not a living Messiah reigning over His people on earth, but He rejected by them, sinners and lost as they were now proved to be; it is Jesus Christ and He crucified, in that character or title which connects Him with the one object for a sinful man: or, as He says Himself here, “that every one that believeth on him may not perish, but have life eternal.” By Him only thus presented one comes to God, all sins being judged and borne in His cross. Hence it is by believing on Him that one has life eternal. The believer looks out of himself to the Lord Jesus.
But this alone might leave the soul, though looking to Christ by faith, without liberty or peace, however truly blessed thus far. Hence the Lord reveals another truth. “For God so loved the world, that he gave his only-begotten Son, that every one that believeth on him should not perish, but have life eternal.” It is no longer the object and absolute need of guilty man, be he Jew or any other. There is now revealed the sovereign love of God, which confines not itself to any limits such as the law, or man under it, had contemplated, but goes out freely and fully to the world, where He was unknown and hated; and this, not in creation or providential mercies, but in such sort as to give His Son, His only-begotten, “that every one that believeth on him may not perish, but have eternal life.” It is grace to the uttermost. It is no question here of a needs-be. There was no moral necessity that God should give His Son; it was His love, not obligation on His part, nor claim on man's. Whatever need there was in man's state was amply met in the cross of the Son of man, and therein was accomplished the atonement or propitiation for the sins of those who believe. But there is incomparably more in the Only-begotten Son given by the God of love, not to the elect nation, but to the world, Thus divine love is manifested as perfectly as His just and holy requirement in judging sin; and this in Christ, the only-begotten Son of God, the suffering but now glorified Son of man, both too displayed in and enjoyed by that life eternal which the believer has in Him.