The Apostle Paul asked this very important question of twelve saved disciples of Christ, at Ephesus.
(1) And it came to pass, that while Apollos was at Corinth, Paul having passed through the upper coasts, came to Ephesus, and finding certain disciples,
(2) He said unto them, Have ye received the Holy Ghost since ye believed? And they said unto him, We have not so much as heard whether there be any Holy Ghost.
(3) And he said unto them, Unto what then were ye baptized? And they said, Unto John's Bapism.
(4) Then Paul said, John verily baptized with the baptism of repentance, saying unto the people, that they should believe on Him which should 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 his hands upon them, and the Holy Ghost came on them, and they spake with tongues, and prophesied.
What is it for?
Power for service, "But ye shall receive power after that the Holy Ghost has come upon you." (Acts 1:8)
Power in witnessing, not only in words, but in claiming healing, deliverance, in prayer, in understanding the Word and power to overcome sin and live a victorious life.
(17) And Ananias went his way, and entered into the house, and putting his hands on him, said, Brother Saul, the Lord (even Jesus that appeared unto thee in the way as thou camest) hath sent me, that thou mightest receive thy sight, and be filled with the Holy Ghost.
(18) And immediately there fell from his eyes as it had been scales, and he received sight forthwith, and arose, and was baptized.
(19) And when he had received meat, he was strengthened.
Should you speak in tongues?
Yes, this is important! This is a gift from God, why should you refuse it? To refuse tongues is to refuse to yield yourself completely to God. If you will not yield completely, you cannot be used completely. It is important that you speak in tongues.
Who is it for?
Only for the 'born again' Christians. The Holy Spirit is not available to the world (the unsaved).
(16) And I will pray the Father, and he shall give you another Comforter, that he may abide with you for ever,
(17) Even the Spirit of truth, whom the world cannot receive, because it seeth him not, neither knoweth him: but ye know him, for he dwelleth with you, and shall be in you.
If you are not sure you are born again, be sure, before you seek the baptism. When you have truly become one of God's children, then "Your heavenly Father will give the Holy Spirit to them that ask Him." (Luke 11:13)
It is not only for the Apostles, or Jews, or people who lives in the days of the Apostles, but for all saved people in every age.
(38) Then Peter said unto them. Repent, and be baptized every one of you in the Name of Jesus Christ, for the remission of sins, and ye shall receive the gift of the Holy Ghost.
(39) For the promise is unto you, and to your children, and to all that are adar off, even as many as the Lord our God shall call.
(40) And with many other words did he testify and ezhort, saying, Save yourselves from this untoward generation.
(41) Then they that gladly received his word, were baptized: and the same day there were added unto them about three thousand souls.
(42) And they contiued stedfastly in the Apostles doctrine and fellowship, and in breaking of bread, and in prayers.
(43) And fear came upon every soul: and many wonders and signs were done by the Apostles.
(44) And all that believed were together, and had all things in common,
It is for all Christians that want a righteous life. "Blessed are they which do hunger and thirst after righteousness: for they shall be filled." (Matthew 5:6)
God Bless you.
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