Can you imagine life without creation? Catholics believe that God the Father is our creator. We acknowledge that He is one person, but we also have faith that the Father is united with the Son and Spirit. Our sinful nature demands reparation. Jesus, also one person, through the gifts of mercy bestowed on us, paid the price for our offenses against God. We are redeemed by the Spirit, a 3rd person, who proceeds from the Father and the Son.
Each person of God is unique and functions individually. Yet, each person is one with each other. They are The Trinity, separate from each other, but completely one as God. Catholics are baptized in the name of the Holy Trinity, one God. We are not baptized in a single person of God, though each person is fully God apart from the Trinity. We do not have 3 different gods, but one God who acts through 3 distinct people for the good of everyone.