We have peace with God through our Lord Jesus Christ because of the love of God that has been poured out into our hearts through the Holy Spirit that has been given to us. There are three feasts (solemnities) that are observed immediately following the Easter celebrations: Most Holy Trinity (which we celebrate today), Corpus Christi, and the Most Sacred Heart of Jesus. These three celebrations invite us to enter more deeply into the life of Jesus Christ so that we can be drawn into the mysteries of our salvation whose culmination is the death and resurrection of our Lord Jesus Christ. We begin this triad of celebrations today by reflecting on the nature of God as a community of persons under the title Most Holy Trinity. 
The Church teaches that in the entire creative and salvific process, God has chosen to reveal the self as a Trinity of persons, that is, as Father, Son, and Holy Spirit. It is a teaching that is revealed to us in the Scriptures. God introduces the self as a community of persons in the creation of the human person (cf. Genesis 1:26: “Let US make man in our own image…”). In the Gospel accounts, we see Jesus always talking about the Father and the Holy Spirit. He always included the Father in everything that he did, either asking the Father to hear his prayers or thanking the Father for hearing his prayers. And in the last couple of Sundays, we have also heard Jesus talking about the Holy Spirit whom he will send to the disciples to continue with the work he (Jesus) had begun. In the Gospel passage for today, Jesus reassures his disciples of this gift of the Holy Spirit. 
God as a trinity of persons is a product of revelation and consequently today’s celebration should not be misconstrued as an attempt to understand how in one God there are three persons. This has already been settled, and as Catholics, it is a revered teaching that informs our daily faith life. All our prayers begin and end with the invocation of the Holy Trinity (as we make the sign of the cross), and it is in the name of the Trinity that we bless ourselves – both within and outside prayer. Rather, by setting apart this day in honor of the Most Holy Trinity, the Church is inviting us to a deeper reflection as to why God chose to reveal the self in a Trinitarian manner.           
In all the three instances (modes) of God’s revelation, there is only one clear motive that can be deduced: God’s desire to be present to creation. 
After creating the world, God did not abandon it or leave it to chart its own course. As a loving, Creator Father, God has remained present to creation. This is the picture that we get from the Genesis creation account. After settling Adam and Eve in the Garden of Eden where they were surrounded with everything that they needed, one would not have faulted God had God decided to detach the self from Adam and Eve and in order to have some “alone” time. But this is not what God does. Rather than recede into the background and watch the first family from afar, God remains present to them to the point of taking occasional strolls in the Garden just to make sure that they are okay (cf. Genesis 3:8). And even after the first family got thrown out of the Garden on account of their rebellion, God did not sever ties with them. God still cared about their welfare and did not wish any harm to come to them (cf. Genesis 4:9-16).   
God’s desire to be more present to creation did not end when the sin of man became so overwhelming to the point of inviting the wrath of God upon the created universe. After the great flood, God elected the nation of Israel in order to walk with her and use her as a means of reaching out to the nations of the world. The story of God’s journeying with Israel reveals a God who loves creation more than creation loves itself. For even after Israel knowingly rebelled against God time and again, God did not give up on her. Every time Israel found herself in a pushed to corner on account of her rebellious actions, God reached out and offered her a new lifeline. 
The climax of God’s desire to remain present to creation was attained when God chose to assume a creaturely nature and dwelt in the midst of creation as one of them. In Jesus Christ, God made man, the revelation of God that only takes place partially in the Old Testament attains its fullness. In Jesus Christ, God made man, we come to know that God desires to be with us because he wants to give us life. Jesus healed the sick, fed the hungry, raised the dead, and re-incorporated into the community those who had been cast out. And when Jesus was about to ascend back to the Father, he gifted the world with the Holy Spirit, the third person of the trinity. Through this Holy Spirit, Jesus continues to be present to his followers in order to continue teaching and guiding them towards the attainment of life eternal. 
The consequence of God revealing the self to us as Father, Son and Holy Spirit is our adoption as God’s sons and daughters, brothers and sisters of Jesus. Jesus Christ, having sacrificially offered himself on our behalf, has given us a new lease of life. We are no longer to be considered solely as descendants of the rebellious Adam and Eve. Through Jesus Christ, we have once again regained our status as heirs of the fullness of life that is available to us in God. We are once again able to call God our Father and claim our fair share of inheritance.