Lord of the Dead and the Living
"For to this end Christ died and lived again, that he might be Lord both of the dead and of the living."
Belonging to Christ has been Paul's emphasis in Romans 14:7-8, and he continues that theme in today's passage when he grounds Christ's ownership of us in Jesus' death and resurrection. "To this end Christ died and lived again, that he might be Lord of both the dead and of the living" (Rom. 14:9).
We may find this verse perplexing at first glance because it seems to indicate that the Son of God was not the Lord of the living and the dead before the successful completion of His ministry, His atonement, and His resurrection for our justification. However, we know that this cannot be the case. As the Word of God who was eternally with God and was eternally God before the incarnation (John 1:1), the Son has been Lord of all from all eternity. All of creation has always belonged to our Creator in the sense that He made it and therefore allows no one to claim any authority over it without His permission (Ex. 19:5). Yet there is a sense in which human beings, since the fall of Adam, have not belonged to the Lord. Having rejected our good God in Adam, the Lord allowed us to enslave ourselves to sin (John 8:34). Since that day, we come into the world not as our Creator's beloved possession but as men and women who belong, in a sense, to another—Satan. Apart from His grace, we are children of the devil no less than the Pharisees were (vv. 39-47). We are by nature children of wrath unless God intervenes to make us His children, to bring us back into His blessed possession (Eph. 2:1-3).
Christ's death and resurrection provide the ransom price by which we are taken from sin and Satan and restored to a state in which we belong to God not merely as creatures but as His children (John 1:9-13). Note that the ransom is not paid to Satan or to sin. Since God established the realm in which we enslaved ourselves to wickedness and remains sovereign over it all, Jesus' life is a ransom paid to our Creator that saves us from His wrath (1 Thess. 1:9-10). We now belong to our heavenly Father as His children because of the work of Christ; we enjoy a new relationship to God, one that is marked by sonship under the "lordship of redemptive relationship," as John Murray writes in his commentary Romans.
All of this forms the theological foundation that explains why we are not to judge those who differ with us on issues where God has left us free to exercise our own discernment (Rom. 14:1-9). Christ made the ultimate sacrifice to buy us back, and because He paid the price, He alone has the right to judge His people.
Coram Deo
That the Son of God is also our Creator should be enough to convince us that the Lord alone has the right to judge us. But God goes a step further, making it clear that we belong to Him because the Son ransomed us from sin and Satan. Since Jesus is our Master, we must accept those whom He accepts, and Romans 14 tells us quite plainly that the Lord has received into His presence those who are mature and strong in the faith as well as those who are immature and weak in the faith.