Those who study Scripture are constantly discovering who God is. Since God is "other" than all of us, we humans can only talk about God in symbols and metaphors. To completely understand God and God's actions is practically and intellectually impossible.
Our Jewish ancestors in the faith were convinced they had at least an inkling about God's personality because Yahweh had worked in their lives throughout their history. The author of Deuteronomy reminds his readers of their uniqueness. "Was it ever heard of? Did a people ever hear the voice of God speaking from the midst of fire, as you did, and live? Or did any god venture to go and take a nation for himself from the midst of another nation. .. ?" God tells us about God by being embedded in our existence. By reflecting on our history, we "... must now know and fix in our heart, that Yahweh is God in the heavens above and on earth below, and that there is no other." We can only find God in heaven by first surfacing God on earth.
That seems to be one of the reasons Paul insists we relate to God as God's children. The Apostle expects Jesus' followers to get rid of the "high falutin" titles which keep God at a distance. For those who imitate the Son of God, God's simply "Abba:" Pop, or Daddy. "All who are led by the Spirit of God are children of God. For you did not receive a spirit of slavery to fall back into fear, but you received a Spirit of adoption ... heirs of God and joint heirs with Christ..."
There's only one problem with relating to God as children relate to their parents: the only child of God with whom we're familiar - Jesus of Nazareth - suffered because of his great love of others. Paul is convinced the only way we can be certain that we, as children, are relating correctly to God is by our suffering. It's in our pain that we most get a glimpse of God's personality. When we're the most helpless, God is the most present.
Along this same line, Matthew teaches that our God isn't a hit and miss element in our history: some days God's here, other days God's absent. In today's gospel pericope, Jesus - God with us - assures his disciples that if they're carrying on his ministry, "I am with you always, until the end of the age." Since there's no ascension in Matthew, we presume the risen Jesus is part of everything we do and are.
Most Christians are surprised to discover that the doctrine of the Trinity - something we expect to find on the first page of our catechisms - wasn't formulated until the Council of Nicea in 325 CE. It took almost 300 years of reflecting on God's presence in their lives before the church could formulate their belief in a Father, Son and Spirit in the symbolic expression of "three persons in one God." The council participants were obviously admitting that our knowledge of God is an ongoing experience.
Perhaps on this particular day we'd best show that we've heard the message our sacred authors are proclaiming by committing ourselves to be extremely reflective about the ways God enters our life. No one theologian, no one sacred author, no one church doctrine can provide us with a complete picture of God. That's why we have to be open not only to God working in our own lives, but to be anxious to discover how God works in the lives of others, even in the lives of those who don't profess faith in Jesus. Anyone who believes one religion has a monopoly on surfacing God's personality has never understood Scripture.