1 And it happened that while Apollos was at Corinth, Paul passed through the inland country and came to Ephesus. There he found some disciples. 2 And he said to them, “Did you receive the Holy Spirit when you believed?” And they said, “No, we have not even heard that there is a Holy Spirit.” 3 And he said, “Into what then were you baptized?” They said, “Into John’s baptism.” 4 And Paul said, “John baptized with the baptism of repentance, telling the people to believe in the one who was to come after him, that is, Jesus.” 5 On hearing this, they were baptized in the name of the Lord Jesus. 6And when Paul had laid his hands on them, the Holy Spirit came on them, and they began speaking in tongues and prophesying. 7 There were about twelve men in all.
Acts 19:5 On hearing about Christian baptism the Ephesian disciples are baptized into the name of Jesus. Does this phrase “into the name of Jesus” mean that the traditional formula “Father, Son and Holy Spirit” was not used? Not at all. Paul, in verse 2, when he hears that these disciples have never heard of the Holy Spirit asks them “…into what then were you baptized?” In other words “How could you have had Christian baptism if you have never heard of the Holy Spirit? If you have had Christian baptism you would have at least heard of Him at your baptism.”
This means that to be baptized into the name of the Lord Jesus (verse 5) includes the mentioning of the Holy Spirit in the act of baptism. This is not a small matter. The doctrine of the trinity is essential to the Christian faith, or to put it more bluntly: if you deny the trinity you are denying the Christian faith.
The God of the Bible is the three Person God. He is the only God who is. You do not worship the God of the Bible if you do not worship Him who is Father, Son and Holy Spirit – three Persons, One God. Do not see this as a small matter. It is crucial. This is worth dying for. Go to the Father today, through your great High Priest, Jesus Christ the Son of God, because of the Holy Spirit who lives in all believers. If there is no trinity you cannot get to God at all.