And it happened, while Apollos was at Corinth, that Paul, having passed through the upper regions, came to Ephesus. And finding some disciples 2 he said to them, “Did you receive the Holy Spirit when you believed?” So they said to him, “We have not so much as heard whether there is a Holy Spirit.” 3 And he said to them, “Into what then were you baptized?” So they said, “Into John’s baptism.” 4 Then Paul said, “John indeed baptized with a baptism of repentance, saying to the people that they should believe on Him who would come after him, that is, on Christ Jesus.” 5 When they heard this, they were baptized in the name of the Lord Jesus. 6 And when Paul had laid hands on them, the Holy Spirit came upon them, and they spoke with tongues and prophesied. Acts 19:1-6 NKJV
An instructor, in a school or college, will give a student a grade of “Incomplete” if the student was passing the class but unable to complete the class or the required assignments. Many Christians are incomplete, not in their faith or righteous standing, but in their understanding of Jesus, the Gospel message, and His many promised blessings.
Apollos was one of those “incomplete” Christians. He was a gifted speaker but he didn’t have a revelation of Jesus Christ and His grace, nor could he—at first—preach a complete message of the Gospel. Although he was a learned man, educated, eloquent, and mighty in the Old Testament Scriptures (Acts 18:24-26), he was yet deficient and insufficient, not complete in his understanding of Jesus’ death and resurrection, and the promise of the Holy Spirit.
Like Apollos, you can only experience and teach to others what you know and understand, notwithstanding your zeal and fervency of spirit (Acts 8:25). When the Apostle Paul came to Ephesus, he readily saw that the disciples of Apollos’ were in some way incomplete, so he asked them the same question that every believer should ask himself: “Did [I] received the Holy Spirit when [I] believed?”
In the New Testament, there are three baptisms specified for Believers in Christ Jesus. Understanding and receiving one or two of them without all of them renders you as incomplete in the revelation of Jesus with respect to all of His promised baptismal blessings, i.e., water baptism (Matt. 28:18), Holy Spirit baptism into the Body of Christ (1 Cor. 12:13), and, don’t leave off, the baptism of the Holy Spirit (Luke 24:49; Acts 1:4, 5, 8)—that would be “incomplete.” Have you received the Holy Spirit since you believed?”