Question 3: How many persons are there in God?
Answer: There are three persons in the one true and living God: the Father, the Son, and the Holy Spirit. They are the same in substance, equal in power and glory.
What would we lose if our faith was one of bare theism instead of Trinitarian theism? In other words, how would our entire theology be different if we believed in one God, but not in the Trinity?
One major difference would be our understanding of who God is in himself. A single-person god (such as Allah in Islam) would be without the attribute of love apart from creating something to love. And in that case, a single-person god would be dependent on creation to have anything to love, much less to express love in any way. We could scarcely say that such a god is, in himself, love. His fundamental identity would be, rather, one of supreme power over us, and relating to us in love would be something that changed him in some way from what he was before. In fact, as we look at Islam, we see just such a conception of god, where Allah is regarded primarily as a god of supreme power. Muslims do not call upon Allah as father, nor do they conceive of him primarily as a god of love (though they do speak of his mercy).
But since we know the truth about God who is eternally Father, Son, and Holy Spirit, we can affirm that, even apart from creation, God has never been without love. Within the life of God himself the Father has loved the Son, and the Son has loved the Father, in the bond of the Spirit forever, and nothing in creation adds to that love a single iota. The Trinitarian God of the Bible is self-contained fullness, dependent on nothing outside of himself.
That realization enables us to affirm what Scripture affirms, namely, that God is love in himself (1 John 4:8). It also puts us in our place, showing us that we add nothing to God’s inner life whatsoever. But we do share in the blessings of God’s love. God did not create us to fill some deficiency in himself. He created us to share in his infinite richness. He is not the empty cup needing to be filled. He is the overflowing fountain, spilling out in grace toward us who are not God, but who through the work of the Son and the gift of the Spirit have been welcomed into God’s own life. That is the true aim of the gospel.
Suggested passage for family or personal reading: Ephesians 1:3-14. Do you see all three Persons of the Trinity here? What does this passage teach about how the three Persons work in unity for our salvation?