The NIV 365 Day Devotional
How Can We Understand the Trinity?
The short answer is that we can’t. Not fully. Finite human beings can’t fully comprehend an infinite God. But we can grapple intelligently with the concept of one God who exists as three distinct and irreducible persons: Father, Son and Spirit.
The Father is referred to as God in Matthew 6:26,30. Jesus is referred to as God in John 1:1,14 and Hebrews 1:6. The Spirit is referred to as God in Acts 5:3-4. All three are referred to as God even though Mark 12:32 tells us that “God is one and there is no other but him.” How do we reconcile this?
The apostle Paul says that God placed clues in creation so we can know more about him (see Ro 1:20). One of the ways we can come to know more about God’s nature is by drawing analogies with things that we can see. And we do see examples of three forms in one essence when we examine God’s creation. Take water, for example. Water is always water, even though it can be experienced in three different forms: liquid, solid (when frozen) and vapor. God is still God even though he can be experienced in three forms—Father, Son and Spirit. Light is another example. Any color of light can be formed from the three primary colors: red, blue and yellow. Even light that appears white and colorless to the human eye is actually a manifestation of those colors.
So nature shows us that one substance with multiple aspects can exist in unity. Keep in mind that these are examples, not explanations. God cannot be explained or understood, but these examples give us a way to begin thinking about the mystery of the Trinity.
Taken from the NIV Starting Place Study Bible.