One God, three Persons
The word Trinity does not appear in the Bible, but Christians use it to gather up what Scripture teaches. There is one God, not three gods. Yet the Father is God, the Son is God, and the Holy Spirit is God, and they are not simply three names for one person acting in different ways.
Jesus told his disciples to baptise in the one name of the Father, and of the Son, and of the Holy Ghost (Matthew 28:19). Paul also joined the Lord Jesus Christ, God, and the Holy Ghost in a blessing for the Corinthian church (2 Corinthians 13:14). These passages do not spell out a philosophical definition, but they show why Christians came to speak of the Trinity.
Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost:
What “Person” means here
In this phrase, Person does not mean three separate human individuals. It means the Father, the Son, and the Holy Spirit truly relate to one another and are distinguishable from one another. The Son prays to the Father, obeys the Father in his earthly mission, and speaks of the Father as someone other than himself (John 17:1-5).
That distinction is real. At the same time, Jesus says that seeing him is seeing the Father, because he perfectly reveals the Father’s character and works (John 14:9-10). Christians are trying to honour both truths: the Son is not the Father, and the Son is fully divine.
Why call the Son “second”?
“Second Person” is not a Bible title for Jesus. It is a later Christian shorthand, often used when speaking of the Father, then the Son, then the Holy Spirit. The number describes an order of naming, not a lesser status. It does not mean there was a time when the Son did not exist.
John begins his Gospel by placing the Word, who becomes flesh in Jesus, with God and as God before creation. Everything that was made came into being through him (John 1:1-3; John 1:14). So the Son belongs on the Creator’s side of the line, not among created things.
The title Son can sound as though Jesus began to exist after the Father, because that is how human fathers and sons work. But Scripture presents the Son as existing before the world and sharing the Father’s glory (John 17:5). Christians have therefore called him the eternal Son.
In the beginning was the Word, and the Word was with God, and the Word was God.
The Son is equal in divine honour
Jesus willingly carried out the Father’s saving purpose, especially in becoming human and giving himself for us. That willing obedience does not make him less than God. In John 5, Jesus says the Son does what he sees the Father doing, gives life, and is to receive the same honour as the Father (John 5:19-23).
This is why calling Jesus the second Person of the Trinity should lead beyond a label. It points to the wonder that the one who walked the roads of Galilee, welcomed sinners, died, and rose again is the eternal Son of God. Read John’s Gospel slowly, and notice both his closeness to the Father and the honour people are called to give him.
That all men should honour the Son, even as they honour the Father. He that honoureth not the Son honoureth not the Father which hath sent him.