Perhaps someone will ask what it means that his garment was divided into so many parts and that lots were cast for his coat. That his garment was divided into four parts was a figure of his four-part Church spread all over the world and equally, that is, harmoniously distributed throughout those parts. This is why elsewhere it says that he would send his Angels to gather his chosen ones from the four winds (Mt 24:31), and what is that but the four parts of the world: the East, the West, the North, the South?
That lots were cast for his cloak symbolizes the unity of all the parts, which is contained by the bond of charity. When the Apostle was about to speak of charity, he said, “I show you the way that surpasses all others” (1 Cor 12:31), and in another place he says, “To know the charity of Christ that surpasses knowledge” (Eph 3:19); and elsewhere: “Above all these things, put on charity, which is the bond of perfection” (Col 3:24). If charity, then, has the surpassing way and surpasses knowledge and is above all other commands, it is fitting that the garment which symbolizes it is said to have been woven from above. It also was seamless so that it would never be unstitched, and it went to a single man because charity gathers all into one. ... (In Ioannem Tr. 118, 4-5; PL 35, 1949-1950).