This Sunday’s lectionary contains two of the New Testament’s clearest Trinitarian references. One is a baptismal formula:
… baptizing them in (or into) the name
of the Father
and of the Son
and of the Holy Spirit
… Matthew 28:19
The other is a benediction.
The grace of the Lord Jesus Christ,
the love of God,
and the communion of the Holy Spirit
be with all of you. 2 Corinthians 13:14
The Christian doctrine of the Trinity can be inferred throughout the New Testament, but seldom are all three persons set in equal apposition. Depending on how it is read, Ephesians 4:4-6 may be another instance.
There is one body and one Spirit
(just as you were called to one hope when you were called)
one Lord, one faith, one baptism;
one God and Father of all, who is over all and through all and in all.
As many scholars have observed, it almost has the form of a confession of faith.
There are other passages of the New Testament in which you find the various names for God, the Lord Jesus and the Holy Spirit together, but not always in ways that require an ontological Trinity as the key to interpretation. And as Larry Hurtado has demonstrated, “binitarian” language is more common in the New Testament than Trinitarian. The New Testament authors did not have a fully developed Nicene theology of the Trinity.
Where we do find explicitly Trinitarian language, we find it in passages related to Christian worship. Doxology precedes doctrine. Or, in the Latin phrase I have frequently repeated, lex orandi lex credendi. How we worship determines what we believe. And you don’t have to have a fully developed theory of the trinity to worship the triune God.