The doctrine of the Trinity is a mystery—a beautiful, world-saving, life transforming, true mystery. As a mystery it can only be understood as far as it is revealed, and even then our finite minds cannot comprehend the infinite reality of our eternal triune God. So we need help in understanding it. We need preachers and teachers to unpack the truth in ways that enable us to more fully know and believe.
One of my favorite explanations of the Trinity is from the Athanasian Creed. As it summarizes and brings together truth this is well worth meditating on throughout the day. In it's explanation it shows that God is unexplainable.
"We worship one God in Trinity, and Trinity in Unity;
Neither confounding the persons nor dividing the substance.
For there is one person of the Father, another of the Son, and another of the Holy Spirit.
But the Godhead of the Father, of the Son, and of the Holy Spirit is all one, the glory equal, the majesty coeternal.
Such as the Father is, such is the Son, and such is the Holy Spirit.
The Father uncreated, the Son uncreated, and the Holy Spirit uncreated.
The Father incomprehensible, the Son incomprehensible, and the Holy Spirit incomprehensible.
The Father eternal, the Son eternal, and the Holy Spirit eternal.
And yet they are not three eternals but one eternal.
As also there are not three uncreated nor three incomprehensible, but one uncreated and one incomprehensible.
So likewise the Father is almighty, the Son almighty, and the Holy Spirit almighty.
And yet they are not three almighties, but one almighty.
So the Father is God, the Son is God, and the Holy Spirit is God;
And yet they are not three Gods, but one God...."