All Christians believe the doctrine of the Trinity. If you do not believe this—that is, if you have come to a settled conclusion that the doctrine of the Trinity is not true—you are not a Christian at all. You are in fact a heretic. Those words may sound harsh, but they represent the judgment of the Christian church across the centuries. Christians in every land unite in proclaiming that our God eternally exists as Father, Son, and Holy Spirit. Those who deny that truth place themselves outside the pale of Christian orthodoxy.
Having said that, I admit that no one fully understands it. It is a mystery and a paradox. Yet I believe it is true.
I can think of at least three reasons for believing in the Trinity:
The Bible teaches this doctrine.
Christians everywhere have always believed it.
No other explanation makes sense....
As you might imagine, the early church struggled mightily over this doctrine. They eventually reduced their belief in the Trinity to two short statements. They concluded that God is …
One in Essence
Three in Person
When we say these things we mean that the Father is God, the Son is God, and the Holy Spirit is God, but they are not three gods but only one God. The Father is not the Son, the Son is not the Spirit, the Spirit is not the Father, but each is God individually and yet they are together the one true God of the Bible.
Have you ever seen the word Godhead? Theologians sometimes use that term when they want to refer to God the Father, God the Son, and God the Holy Spirit as three divine Persons in one God.
At this point I think we should acknowledge the chief objection to the doctrine of the Trinity, which is that it is absurd. Sometimes the Jehovah's Witnesses (who pointedly deny the Trinity) ridicule it with this little equation: 1 + 1 + 1 = 3. In their minds Christians worship three Gods, not one. The answer is quite simple. The doctrine of the Trinity is not absurd if that's what the Bible teaches. Furthermore, there is more than one way to play with equations. You could also say it this way: 1 x 1 x 1 = 1!
Excerpted from "God in Three Persons: A Doctrine We Barely Understand" by Keep Believing Ministries (used by permission).