4 Some one, perhaps, may inquire what is signified by the division that was made of His garments into so many parts, and of the casting of lots for the coat. The raiment of the Lord Jesus Christ parted into four, symbolized His quadripartite Church, as spread abroad over the whole world, which consists of four quarters, and equally, that is to say, harmoniously, distributed over all these quarters. On which account He elsewhere says, that He will send His angels to gather His elect from the four winds: and what is that, but from the four quarters of the world, east, west, north, and south?
But the coat, on which lots were cast, signifies the unity of all the parts, which is contained in the bond of charity. And when the apostle is about to speak of charity, he says, “I show you a more excellent way;” and in another place, “To know also the love of Christ, which far excels knowledge;” and still further elsewhere, “And above all these things charity which is the bond of perfectness.” If, then, charity both has a more excellent way, and far excels knowledge, and is enjoined above all things, it is with great propriety that the garment, by which it is signified, is represented as woven from the top. And it was without seam, that its sewing might never be separated; and came into the possession of one man, because He gathers all into one.
Just as in the case of the apostles, who formed the exact number of twelve, in other words, were divisible into four parts of three each, when the question was put to all of them, Peter was the only one that answered, “You are the Christ, the Son of the living God;” and to whom it was said, “I will give unto you the keys of the kingdom of heaven,” as if he alone received the power of binding and loosing: seeing, then, that one so spoke in behalf of all, and received the latter along with all, as if personifying the unity itself; therefore one stands for all, because there is unity in all.
Whence, also, after here saying, “woven from the top,” he added, “throughout.” And this also, if referred to its meaning, implies that no one is excluded from a share thereof, who is discovered to belong to the whole: from which whole, as the Greek language indicates, the Church derives her name of Catholic. And by the casting of lots, what else is commended but the grace of God? For in this way in the person of one it reached to all, since the lot satisfied them all, because the grace of God also in its unity reaches unto all; and when the lot is cast, the award is decided, not by the merits of each individual, but by the secret judgment of God.
Source: Tractates on the Gospel of John (New Advent)