The Trinity

Though you don't find the word 'Trinity' in the Bible,
the doctrine is clearly portrayed in the Bible
through what is said about the tri-unity of God:

God is One

The Father is God
The Father is not the Son
The Father is not the Holy Spirit

The Son is God
The Son is not the Father
The Son is not the Holy Spirit

The Holy Spirit is God
The Holy Spirit is not the Father
The Holy Spirit is not the Son

See the list of scriptures clearly portraying the Father, Son and Holy Spirit as possessing the same essence with differing identities:
(Hint you can enlarge it with a pull-down arrow)