There is one true God who exists in three persons — Father, Son and Holy Spirit.
"Hear, O Israel: The Lord our God, the Lord is one." Deuteronomy 6:4 (ESV)
"And when Jesus was baptized, immediately he went up from the water, and behold, the heavens were opened to him, and he saw the Spirit of God descending like a dove and coming to rest on him; and behold, a voice from heaven said, 'This is my beloved Son, with whom I am well pleased.' " Matthew 3:16-17 (ESV)
"And Jesus came and said to them, 'All authority in heaven and on earth has been given to me. Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, teaching them to observe all that I have commanded you. And behold, I am with you always, to the end of the age.' " Matthew 28:18-20 (ESV)