Like the simple cup and the little piece of bread that are in front of us today, baptism also uses the ordinary things of life and makes them extraordinary. Through these simple things the love of God is revealed. As you know, when we baptize someone, we use water. Water has often been used as an illustration of the Trinity. Three can be one.
Water can have three characteristics.
It can be a solid, as ice. It can be a gas, as steam. It can be a liquid, as the water we wash with and drink. It's all water, yet it takes three different forms. So God can be three and still God is one.