Pillar Focus The Apostles Creed "I believe in the Father... in his only Son... and in the Holy Spirit."
Most Christians believe that there is only one God. However, we also believe that this one God manifests himself in three distinct persons. The first person is the Father, who is the almighty creator of Heaven and earth. The second is the Son, Jesus Christ, a man, who redeemed us by dying on the cross. The third person is the Holy Spirit , who is given to us by the Father and Son for the sake of making us holy. All three are worshiped and glorified as the one true God.
Does all this sound a little complicated? If you really think about it, it is! The belief in a triune (or trinitarian) God is the central mystery of our Catholic faith. Its full understanding is far beyond human reason. However, we know that it's true, primarily, because it has been revealed to us by Christ. Take the following verse for example, where Jesus commissions his apostles to baptize people in a specific way:
"Therefore go and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit" (Mt 28:19).The great mystery of the Trinity has profound implications. It means that whatever attributes and power God the Father has, God the Son and God the Holy Spirit have as well. "Thus, God the Son and God the Holy Spirit are also eternal, omnipresent, omnipotent, infinitely wise, infinitely holy, infinitely loving, omniscient."
Compendium (scroll to 44-49) The Trinity