Although the New Testament never defines the Trinity explicitly, there are a number of New Testament passages take us their implicitly. For example:
Therefore go and make disciples of all nations, baptising them in the name of the Father and of the Son and of the Holy Spirit (Matthew 28:19)
Because you are sons, God sent the Spirit of his Son into our hearts, the Spirit who calls out, “Abba, Father.” (Galatians 4:6)
I keep asking that the God of our Lord Jesus Christ, the glorious Father, may give you the Spirit of wisdom and revelation, so that you may know him better. (Ephesians 1:17)
May the grace of the Lord Jesus Christ, and the love of God, and the fellowship of the Holy Spirit be with you all. (2 Corinthians 13:14)
I have to say, the last is my favourite. What’s your understanding of the Trinity? How do you prefer to explain it?