It refers to giving food to the hungry and water to the thirsty, welcoming strangers, clothing the naked, caring for the sick, and visiting those in prison. Obeying All that Jesus has commanded is not limited to doing religious things in public where people can see you and praise you for what you have done. It includes the secular and private arenas of life as well. If all authority is Jesus Christ's, then all of life is reclaimed by him as well, in heaven and on earth. His disciples know that and put it into practice.
Today is the Festival of the Holy Trinity.
It is the only day in our liturgical calendar set aside for a doctrine rather than an event or a saint. That is unfortunate, because the original emphasis was not on the threefoldness but on the unity of the godhead. We do not believe in three gods, but in one God in three persons. The early church's belief was grounded in God being fully present as the Father-creator of all things, the Son Jesus Christ, and the Holy Spirit. The doctrine was formulated to affirm that these three represent one God, not three gods, while at the same time affirming that God is manifested fully in all three.