Catechism of the Catholic Church

Jesus himself affirms that God is "the one Lord" whom you must love "with all your heart, and with all your soul, and with all your mind, and with all your strength." At the same time Jesus gives us to understand that he himself is "the Lord." To confess that Jesus is Lord is distinctive of Christian faith. This is not contrary to belief in the One God. Nor does believing in the Holy Spirit as "Lord and giver of life" introduce any division into the One God: (446, 152, 42) > We firmly believe and confess without reservation that there is only one true God, eternal, infinite (immensus) and unchangeable, incomprehensible, almighty, and ineffable, the Father and the Son and the Holy Spirit; three persons indeed, but one essence, substance or nature entirely simple.