Note: When I explain The Trinity, it goes like this, The Father, The Son, and The Holy Spirt are one (1), simply meaning they agree on everything (no one else in the history of histories has ever run across two people who agree on "everything"). Since they agree on everything, they are co-equally God. Three different job descriptions, totally equal in authority.
Plain and simple, at least to me, below is the way I use to try and explain it; it's long but clearly shows; while I believe it to be Biblically correct, I see why it can be challenging to understand; much less be able to explain to someone who "knows not the Scripture, nor the power of God:
Matthew 22:29 But Jesus replied to them, You are wrong because you know neither the Scriptures nor God’s power.
Long Version - - - The Trinity The doctrine of the Trinity is one of the most challenging concepts in Christianity to wrap our minds around. And yet, it is also one of the most important. The Trinity is the doctrine that says there is one God in three persons, the Father, the Son, and the Holy Spirit. This may sound contradictory, but it is not; it is a mystery.
The word “Trinity” is not found in the Bible. However, Theophilus of Antioch first used it in the late second century. It comes from the Latin word Trinitas, which means “three” or “triple.” * (“12 Things to Know and Share About the Holy Trinity - NCR”). The doctrine of the Trinity was first formally affirmed at the Council of Nicea in 325 A.D.
The concept of the Trinity can be difficult to grasp because it goes against our natural way of thinking. We are used to thinking in terms of binary opposites—such as light/dark, hot/cold, up/down, etc.
But when it comes to God, we must think beyond these opposites. We must think in terms of Threeness or triunity. How can there be one God in three persons? That is indeed a mystery. But it is a mystery we can begin to understand by looking at how we are made in God’s image. Just as we are body, soul, and spirit, so is God three-in-one.
Each person of the Trinity has a unique role:
God, The Father, the creator of heaven and earth (Genesis 1:1), is the source of all life and love.
The Son is our Savior, who came to rescue us from our sins and give us new life.
The Holy Spirit lives inside us, supplying the power needed to live as The Lord intends us to live and love.
While each member of the Trinity has a unique role, they are all co-equal and co-eternal with one another. They are all perfect expressions of who God is and work together for our good and His glory.
When we try to wrap our minds around the concept of the Trinity, we will undoubtedly come up against some roadblocks. But that’s okay! We don’t have to fully understand everything about God to believe in Him or follow Him.
As C.S Lewis once said, “I believe in Christianity as I believe that the sun has risen not only because I see it but because by it, I see everything else."