Holy Spirit Encounter
The Sign & Seal of the New Covenant
Baptism in the Holy Spirit is the only sign of the New Covenant which God makes with His Church. The baptism in the Holy Spirit is separate and distinct from water baptism. Jesus himself is the one who baptizes with the Holy Spirit. He gives it so that we will be endowed with supernatural power to preach the Gospel to the ends of the earth (Acts 1:8). (See scriptures below...)
Jesus commanded water baptism in the Great Commission: “Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit” (Matthew 28:19). It represents rebirth in Christ - the washing away of sins and dying to our old self. But water baptism and Holy Spirit baptism were usually separate events.
1 Corinthians 12:13 (ESV) For in one Spirit we were all baptized [a sign evidenced by speaking in other tongues] into one body—Jews or Greeks, slaves or free—and all were made to drink of one Spirit.
So, one of the reasons God has given the gift of speaking in other tongues is to combat racial and cultural prejudices among different people groups and thus promote Christian unity among diverse peoples. Speaking in other tongues is a sign that a person is in fact a Christian and has a guarantee of - a down payment towards - our full inheritance in the Kingdom of God when we are brought into the new heavens and new earth - heaven on earth. The other sign a person is a Christian is that they are producing fruit in keeping with repentance (Matt 3:8)
2 Corinthians 1:20-22 (ESV) 20 For all the promises of God find their Yes in him [Jesus Christ]. That is why it is through him that we utter our Amen to God for his glory. 21 And it is God who establishes us with you in Christ, and has anointed us, 22 and who has also put his seal on us [the sign of speaking in other tongues] and given us his Spirit in our hearts as a guarantee.
Ephesians 1:13-14 (NET) 13 And when you heard the word of truth (the gospel of your salvation)—when you believed in Christ—you were marked with the seal [the sign of speaking in other tongues] of the promised Holy Spirit, 14 who is the down payment [guarantee] of our inheritance, until the redemption of God’s own possession, to the praise of his glory.
What follows is the evidence from scripture that baptism in the Holy Spirit is a sign and the seal of the New Covenant and it is a separate event from water baptism.
Notice below how these early 1st century Christians used speaking in other tongues as an irrefutable indication that a person was indeed a believer. It was used like credentials certifying a person's inheritance in the Kingdom of God as a child of God (Acts 10:44-48, Acts 11:15-16). Only a born again believer through faith in Christ Jesus, a true child of God, has the indwelling Holy Spirit.
John 1:32-33 (NET)
32 Then John testified, “I saw the Spirit descending like a dove from heaven, and it remained on him. 33 And I did not recognize him, but the one who sent me to baptize with water said to me, ‘The one on whom you see the Spirit descending and remaining—this [Jesus] is the one who baptizes with the Holy Spirit.’
Luke 11:11-13 (NET)
11 What father among you, if your son asks for a fish, will give him a snake instead of a fish? 12 Or if he asks for an egg, will give him a scorpion? 13 If you then, although you are evil, know how to give good gifts to your children, how much more will the heavenly Father give [the good gift of] the Holy Spirit to those who ask him!”
Acts 1:4-5 (NET)
4 While he was with them, he declared, “Do not leave Jerusalem, but wait there for what my Father promised, which you heard about from me. 5 For John baptized with water, but you will be baptized with the Holy Spirit not many days from now.”
Acts 2:1-4 (NET)
1 Now when the day of Pentecost had come, they were all together in one place. 2 Suddenly a sound like a violent wind blowing came from heaven and filled the entire house where they were sitting. 3 And tongues spreading out like a fire appeared to them and came to rest on each one of them. 4 All of them were filled with the Holy Spirit, and they began to speak in other languages as the Spirit enabled them.
Matthew 12:34b (NET)
For the mouth speaks from what fills the heart.
2 Corinthians 1:21-22 (NET)
21 But it is God who establishes us together with you in Christ and who anointed us, 22 who also sealed us and gave us the Spirit in our hearts as a down payment [guarantee].
Ephesians 1:13-14 (NET)
13 And when you heard the word of truth (the gospel of your salvation)—when you believed in Christ—you were marked [by speaking in other tongues] with the seal of the promised Holy Spirit, 14 who is the down payment [guarantee] of our inheritance, until the redemption of God’s own possession, to the praise of his glory.
Acts 10:44-48 (NET)
44 While Peter was still speaking these words, the Holy Spirit fell on all those who heard the message. 45 The circumcised believers who had accompanied Peter were greatly astonished that the gift of the Holy Spirit had been poured out even on the Gentiles, 46 for  they heard them speaking in tongues and praising God. Then Peter said, 47 “No one can withhold the water for these people to be baptized [a separate event from Spirit baptism], who have received the Holy Spirit just as we did [at Pentecost], can he?” 48 So  he gave orders to have them [water] baptized in the name of Jesus Christ. Then they asked him to stay for several days.
Acts 11:15-16 (NET)
15 Then as I began to speak, the Holy Spirit fell on them just as he did on us at the beginning [at Pentecost]. 16 And I remembered the word of the Lord, as he used to say, ‘John baptized with water, but you will be baptized with the Holy Spirit.’
Acts 8:14-17 (NET)
14 Now when the apostles in Jerusalem heard that Samaria had accepted the word of God, they sent Peter and John to them. 15 These two went down and prayed for them so that they would receive the Holy Spirit. 16 (For the Spirit had not yet come upon any of them, but  they had only been [water] baptized in the name of the Lord Jesus.) 17 Then  Peter and John placed their hands on the Samaritans, and they received the Holy Spirit.
Acts 9:17-19 (NET)
17 So Ananias departed and entered the house,  placed his hands on Saul and said, “Brother Saul [Paul], the Lord Jesus, who appeared to you on the road as you came here, has sent me so that you may see again and be filled with the Holy Spirit.” 18 Immediately something like scales fell from his eyes, and he could see again.  He got up and was [water] baptized, 19 and after taking some food, his strength returned.
1 Corinthians 14:18-19 (NET)
18 I thank God that I [Paul] speak in tongues more than all of you, 19 but in the church I want to speak five words with my mind to instruct others, rather than ten thousand words in a tongue.
1 Corinthians 14:22 (NET)
So then, tongues are a sign not for believers but for unbelievers. Prophecy, however, is not for unbelievers but for believers.
Acts 19:1-6 (NET)
1 While Apollos was in Corinth, Paul went through the inland regions and came to Ephesus. He found some disciples there 2 and said to them, “Did you receive the Holy Spirit when you believed?” They replied, “No, we have not even heard that there is a Holy Spirit.” 3 So Paul said, “Into what then were you baptized?” “Into John’s baptism,” they replied. 4 Paul said, “John baptized with a baptism of repentance, telling the people to believe in the one who was to come after him, that is, in Jesus.” 5 When they heard this,  they were [water] baptized in the name of the Lord Jesus, 6 and when  Paul placed his hands on them, the Holy Spirit came upon them, and they began to speak in tongues and to prophesy.
The Sign & Seal of the New Testament Covenant
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