There are 46 Books in the Old Testament (OT) and 27 Books in the New Testament (NT) for a total of 73 books of the Bible. None of them use the word Trinity. Yet, the Catholic Church for 2000 years has proclaimed the Trinity as dogma: three Persons in one God---God the Father, God the Son, God the Holy Spirit. Likewise, all Eastern Orthodox Churches and most Protestant denominations believe in the Trinity. That's two billion Christians who believe in a word that never appears in the Bible.

Even though the word Trinity doesn't appear, we find references to it in the NT and hints of it in the OT. Gen 18:1-3 says, "The Lord appeared to Abraham by the oaks of Mamre, as he sat at the door of his tent in the heat of the day. He lifted up his eyes and looked, and behold, three men stood in front of him. When he saw them, he ran from the tent door to meet them, and bowed himself to the earth, and said, 'My Lord, if you have found favor in your sight, do not pass by your servant.'" We also find three passages in the Book of Genesis where God speaks of Himself in the plural form: 1:26, 3:22, and 11:7.

Why doesn't the OT definitively speak of the Trinity, instead of just hinting at it? There's a simple reason. God, in His infinite wisdom, knew that the Trinity would be a difficult mystery for man to understand. In ancient times monotheism (belief in one God) was less common than polytheism (belief in multiple Gods). God's chosen people, the Israelites, were surrounded by tribes and nations that worshipped multiple Gods. God chose to slowly reveal the mystery of the Trinity to man, because His most important truth for the Israelites was that they understood that there was only one God. The Catechism of the Catholic Church (CCC 684) speaks to this idea when it quotes the 4th century saint, Gregory of Nazianzus, who said, "The Old Testament proclaimed the Father clearly, but the Son more obscurely. The New Testament revealed the Son and gave us a glimpse of the divinity of the Spirit. Now the Spirit dwells among us and grants us a clearer vision of Himself. It was not prudent, when the divinity of the Father had not yet been confessed, to proclaim the Son openly and, when the divinity of the Son was not yet admitted, to add the Holy Spirit as an extra burden."

While the word Trinity doesn't appear in the NT, the NT does reveal the Catholic teaching of three persons in One God. 1 Cor 12:4-6, 2 Cor 13:13, and Mt 28:19 are unmistakable examples. Jesus tells his disciples in Mt 28:19, "Go, therefore, and make disciples of all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Spirit." It's important to notice that Saint Matthew asserts "in the name of" not "in the names of:" singular, not plural. Father, Son, and Holy Spirit are not separate Gods; they are separate and distinct Persons in One God. You ask, "Since when does one plus one plus one equal one and not three?" Answer: for ever and ever when we speak of the Holy Trinity.

No one can embrace Christianity without believing in the Holy Trinity. Yet, this central truth of our Catholic faith is a mystery for which finite minds cannot completely comprehend the true nature of an infinite God; although, many have tried. Saint Patrick used the analogy of a shamrock to explain the Trinity to the Celtic peoples. I recently heard two other analogies.

What is water? H2O. H2O is water in its liquid state, ice in its solid state, and steam in its heated state. Water is H2O; ice is H2O; steam is H2O; but water isn't ice and ice isn't steam. Yet, all three are H2O.

I am one distinct man; yet, within my family I have three relationships. I'm John the father because I have sons and daughters. I'm John the son because I have a father. I'm John the spouse because I have a wife. John the father is not the same as John the son; and John the son is not the same as John the spouse; but all three persons are John the man. My relationship as father is not the same as my relationship as son; nor, is my relationship as son the same as my relationship as spouse: three distinct relationships, yet one man.

Why is recognition and acceptance of the dogma of the Trinity central to Catholic teaching? Let's turn to the Catechism for our answer. CCC 221 states, "God's very being is love. By sending his only Son and the Spirit of Love in the fullness of time, God has revealed His innermost secret: God Himself is an eternal exchange of love, Father, Son, and Holy Spirit, and He has destined us to share in that exchange." Love is always strongest within the human family, because human family love is a reflection of the infinite love between the three Persons of the Trinity. CCC 2205 goes into this, saying, "The Christian family is a communion of persons, a sign and image of the communion of the Father and the Son in the Holy Spirit. In the procreation and education of children it reflects the Father's work of creation. It is called to partake of the prayer and sacrifice of Christ. Daily prayer and the reading of the Word of God strengthen it in charity. The Christian family has an evangelizing and missionary task." Pope John Paul II says, "God in His deepest mystery is not a solitude but a family, since He has in Himself fatherhood, sonship, and the essence of the family, which is love."

Our belief in the Trinity is so central to our Catholic faith that we start and end every Mass by proclaiming it in the name of the Father, and of the Son, and of the Holy Spirit.

For more insight read CCC paragraphs 232-237, 249-267, 684, 689, 1066, 2205, 2655. Also, pull out your Catholic" Bible and reference Gen 1:26; 3:22; 11:7; Prov 8:22-31; Ezik 11:19-20; Mt 3:13-17; Mk 1:9-11; Lk 3:21-22; Jn 1:1-18; 15:26; 1 Cor 12:4-6, 2 Cor 13:13; Gal 4:4.