37. Why does one profess belief that there is only one God?
Belief in the one God is professed because he has revealed himself to the people of Israel as the only One when he said, “Hear, O Israel, the Lord our God is one Lord” (Deuteronomy 6:4) and “there is no other” (Isaiah 45:22). Jesus himself confirmed that God is “the one Lord” (Mark 12:29). To confess that Jesus and the Holy Spirit are also God and Lord does not introduce any division into the one God.
(CCC 200-202, 228)
(Source: teopoli.com, via catechismofthecatholicchurch)
