In Acts 18 we find Paul making a promise. “They arrived at Ephesus, where Paul left Priscilla and Aquila. He himself went into the synagogue and reasoned with the Jews. When they asked him to spend more time with them, he declined. But as he left, he promised, "I will come back if it is God's will." Then he set sail from Ephesus.” (Acts 18 vv 19-21)
Now he keeps that promise and journeys back inland to visit Ephesus once again. Doubtless he went looking for the people he had met earlier and was prompted to ask them this leading question - "Did you receive the Holy Spirit when you believed?" It would seem that he detected something incomplete about their Christian life and experience. It turned out they had not been baptised into the name of Jesus, and had never heard anything about the Holy Spirit. Two major areas of concern to say the least!
Both of these are matters that would concern a Pastor deeply. They had not really understood who Jesus was and what He had done – and so Paul explained and baptised them ‘into the name of the Lord Jesus’. What follows is a near repeat of Pentecost, with the disciples receiving the Holy Spirit, speaking in tongues and prophesying.
What fundamental issues these are! Without an understanding of the person of Jesus, and being baptised ‘into Christ’, and not experiencing the power and presence of the Holy Spirit, make for a faith that is seriously deficient. Yet many Christians still soldier on with the same deficiencies of faith and experience! No small wonder the Church of Christ appears only half alive at times.
Seeing the opportunities in front of him, Paul preached first in the Synagogue, and then in a public lecture hall, staying in Ephesus for over two years. His love for the people there grew through adversity, making his eventual letter to them one of the most theologically and practically significant in the whole New Testament.

For reflection: Could you testify to life in Christ by the power of the Holy Spirit?