This is why Paul can say in Acts 19:2 when he meets the confused disciples of John the Baptist, “Did you receive the Holy Spirit when you believed?” What would a contemporary Protestant evangelical say in response to that question? I think we would say something like, “I thought we automatically received the Holy Spirit when we believed. I don’t understand how you can even ask the question.” How could Paul ask that question? He could ask it, I think, because receiving the Holy Spirit is a real experience. There are marks of it in your life. And the best way to test the faith of these so-called disciples is to ask them about their experience of the Spirit. This is no different than what Paul said in Romans 8:14, “All who are led by the Spirit are the sons of God” (see 2 Cor. 13:5 and 1 John 3:24; 4:12-13).
I sometimes fear that we have so redefined conversion in terms of human decisions and have so removed any necessity of the experience of God’s Spirit, that many people think they are saved when in fact they only have Christian ideas in their head not spiritual power in their heart.” —John Piper (via solideogloriaa)