“[T]he state, though in fact a religious institution, incapable of securing its proper ends without recognizing religious obligation, is not a church. Christ’s church, of which he claims to be the Head, is not of this world, but has its own existence, organization, and officers entirely distinct from the state. He has constituted it not for the purpose of bearing the sword, nor for the punishing of crimes, but rather that by moral means it may edify itself, teach and illustrate the Word of God, propagate the Gospel, and maintain the worship and ordinances which he has prescribed.”