Specification and Exclusion
Whenever God makes a specification, it excludes alternatives.
For example, in the Law of Moses, God specified that priests come from the tribe of Levi. Therefore, in order for Jesus to be a priest, the law had to be changed. "For it is evident that our Lord was descended from Judah, a tribe with reference to which Moses spoke nothing concerning priests" (Hebrews 7:14). Moses (in speaking for God) did not have to say, "Priests shall not come from the tribe of Reuben, Simeon, Judah, Dan, Naphtali, Gad, Asher, Issachar, Zebulun, Manasseh, Ephraim, or Benjamin." Whenever he specified that priests come from the tribe of Levi, it excludes priests coming from any other tribe. Whenever God makes a specification, it excludes alternatives.
Going back further in our Old Testaments, we find God commanding Noah to make an ark out of "gopher wood" (Genesis 6:14 NASB). Would it have been all right for Noah to make the ark out of some other kind of wood? God didn’t say not to. But we understand that when God specified gopher wood, it excluded other kinds of wood. Whenever God makes a specification, it excludes alternatives.
Turning to the law of Christ as revealed in the New Testament, we find that God wants us to immerse believers (Mark 16:16). What then of the practice of sprinkling infants? God never said, "You shall not sprinkle infants." But when God specified that we immerse believers, it excluded the practice of sprinkling infants. Whenever God makes a specification, it excludes alternatives.
When it comes to church government, we find that Christ is the head of the church (Ephesians 5:23), with each congregation being ruled by elders (1 Peter 5:1-3). What then of having a pope? God never said, "You shall not have a pope." But when God specified the church government he wanted, he excluded the practice of having a pope.
I think that I shall never see,
A Church that's all it ought to be;
A Church whose members never stray,
Beyond the straight and narrow way.
A Church that has no empty pews,
Whose preacher never had the blues;
Where elders "eld" and deacons "deek"
And none is proud, and all are meek.
Where gossips never peddle lies,
Or make complaints, or criticize,
Whose members all are sweet and kind,
And to each other's faults are blind.
Such congregations there may be,
But none of them are known to me;
So let us work and pray and plan,
To make this church the best we can.
Home