The New Testament Revelation
The revelation of the trinity working in unity to fulfil the divine plan of redemption begins with the incarnation of the Son. When Gabriel addressed Mary regarding the uniqueness of her pregnancy and the one to whom she would give birth, he informed her: "The Holy Spirit will come upon you, and the power of the Highest will overshadow you; therefore, also, that Holy One who is to be born will be called the Son of God" (Luke 1:35-36 NKJV).
The occasion of the baptism of Jesus gives us a clear view of the trinity in action as He commenced His public ministry in the land of Israel. The gospel of Matthew records: 'And Jesus, when He was baptized, went up straightway out of the water: and, lo, the heavens were opened unto Him, and he saw the Spirit of God descending like a dove, and lighting upon Him: And lo a voice from heaven, saying, This is My beloved Son, in whom I am well pleased' (Matthew 3:16-17).
The book of Hebrews states the following concerning the death of Christ: 'For if the blood of bulls and goats and the ashes of a heifer, sprinkling the unclean, sanctifies for the purifying of the flesh, how much more shall the blood of Christ, who through the eternal Spirit offered Himself without spot to God, cleanse your conscience from dead works to serve the living God?' (Hebrews 9:13-14 NKJV). The Son in the power of the Holy Spirit offered Himself as a perfect and unblemished sacrifice before God the Father for our cleansing.
Matthew's record of the Lord's great commission to the apostles reads: 'And Jesus came and spoke to them, saying, “All authority has been given to Me in heaven and on earth. Go therefore and make disciples of all the nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, teaching them to observe all things that I have commanded you; and lo, I am with you always, even to the end of the age.” Amen' (Matthew 28:18-20 NKJV). Note the singular name of the three persons of the trinity indicating their united identity. In baptism the believer is expressing association with the very Godhead.
John, the seer of Patmos, who received and recorded the 'Revelation of Jesus Christ' writes a trinitarian greeting to the seven assemblies in the Roman province of Asia Minor in the following words: 'Grace be unto you, and peace, from Him which is, and which was, and which is to come; and from the seven Spirits which are before His throne; And from Jesus Christ, who is the faithful witness, and the first begotten of the dead, and the prince of the kings of the earth' (Revelation 1:4-5a). 'Him which is and which was and which is to come' corresponds to and expounds the Old Testament name Jehovah mostly translated, 'The Lord.' 'The seven Spirits which are before His throne' expresses the fullness of the power and the completeness of the ministry of the Holy Spirit. The threefold designation of 'Jesus Christ' amplifies the glory of His person which is fittingly followed by a beautiful doxology of praise to Him (vv 5b-6). This greeting therefore forms one of the most powerful trinitarian statements of the Bible.
How Should I Respond?
Again it must be stressed that the truth of the holy trinity is known because of divine revelation, not human reasoning or investigation. It is revelation to be accepted by faith in the recognition that there is a level beyond which we cannot go in our understanding because of our finite minds. Proud men often think they know better than the Bible and what they don't understand they dismiss as meaningless or impossible rather than yielding in humble submission to the glory of almighty God. Arrogance is always the road to ruin.
Worship is the proper response of the human heart and worship begins with a recognition of what I am and who God is. True worshipers are those who have submitted in repentance before God, accepted His Son as Lord and Saviour by faith, and have experienced the indwelling of the Holy Spirit.