Are you questioning the fundamental belief statement or are you really questioning the Bible upon which the statement is based?
1Jo 5:7 For there are three that bear record in heaven, the Father, the Word, and the Holy Ghost: and these three are one.
Joh 1:14 And the Word was made flesh, and dwelt among us, (and we beheld his glory, the glory as of the only begotten of the Father,) full of grace and truth.
Mat 28:19 Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost:
1Pe 1:5 Who are kept by the power of God through faith unto salvation ready to be revealed in the last time.
Eph 3:5 Which in other ages was not made known unto the sons of men, as it is now revealed unto his holy apostles and prophets by the Spirit;
1Ti 1:17 Now unto the King eternal, immortal, invisible, the only wise God, be honour and glory for ever and ever. Amen.
1Ti 6:15 Which in his times he shall shew, who is the blessed and only Potentate, the King of kings, and Lord of lords;
1Ti 6:16 Who only hath immortality, dwelling in the light which no man can approach unto; whom no man hath seen, nor can see: to whom be honour and power everlasting. Amen.
Rev 19:6 And I heard as it were the voice of a great multitude, and as the voice of many waters, and as the voice of mighty thunderings, saying, Alleluia: for the Lord God omnipotent reigneth.
From Websters Dictionary:
Omnipotent
OMNIP'OTENT, a. [supra.]
1. Almighty; possessing unlimited power; all powerful. The being that can create worlds must be omnipotent.
2. Having unlimited power of a particular kind; as omnipotent love.