The love of God is the first and great commandment. But love of our neighbor is the means by which we obey it. Since we cannot see God directly, God allows us to catch sight of him through our neighbor. By loving our neighbor we purge our eyes to see God. So love your neighbor and you will discover that in doing so you come to know God.
Augustine of Hippo
He alone loves the Creator perfectly who manifests a pure love for his neighbor.
Bede
In order to love our neighbor properly we must seek God’s help. It is not possible to love our neighbor with a pure heart without loving God first. We cannot pass on God’s love if we do not possess God’s love ourselves.
Bernard of Clairvaux
You can never love your neighbor without loving God.
Bossuet
Though we do not have our Lord with us in bodily presence, we have our neighbor, who, for the ends of love and loving service, is as good as our Lord himself.
Teresa of Avila