Holy Spirit Baptism

This article is very good and I mostly agree with it :)

Why is the Assemblies of God so committed to the doctrine of the baptism in the Holy Spirit with the initial evidence of speaking in tongues?

The Baptism in the Holy Spirit is a vital experience of the Christian life. It is a special work of the Spirit beyond salvation. On the Day of Pentecost, disciples who had already made a decision to follow Jesus "were filled with the Holy Spirit and began to speak in other tongues" (Acts 2:4). Paul asked the Ephesians disciples if they had received the Holy Spirit, after which "the Holy Spirit came on them, and they spoke in tongues" (Acts 19:2). New Testament believers were constantly challenged to be filled with the Spirit (Acts 1:4,5; Ephesians 5:18). The Assemblies of God is committed to the baptism in the Holy Spirit because the experience is such an important focus of New Testament Christianity.

Though many non-Pentecostals teach a baptism in the Holy Spirit without speaking in tongues, the position of the Assemblies of God is clearly declared in Section 8 of its Statement of Fundamental Truths: "The baptism of believers in the Holy Spirit is witnessed by the initial sign of speaking with other tongues as the Spirit of God gives them utterance (Acts 2:4)." The evidence always occurred (and still does today) at the time believers were baptized in the Spirit, not at some indeterminate future time.

Speaking in tongues is the only phenomenon mentioned every time Scripture supplies details concerning the Baptism experience. Of the five instances in Acts which recount the experience of believers being baptized in the Spirit, three supply details. Speaking in tongues is the only one that occurs each time (Acts 2, 10, 19). In the Acts 10 account, tongues is specifically mentioned as proof that "the gift of the Holy Spirit had been poured out even on the Gentiles. For they heard them speaking in tongues" (Acts 10:45, 46). The relationship between the phenomenon and the experience cannot be ignored.

In the two cases where details are not supplied, circumstances strongly imply that speaking with other tongues accompanied the experience. In Acts 8 Simon saw something (most likely tongues) that prompted him to offer money for the power to impart such a gift. In Acts 9 Saul (who became Paul) is filled with the Spirit without the mention of any details. However, Paul later testified, "I speak in tongues more than all of you" (1 Corinthians 14:18). It is logical to conclude that he began speaking in tongues when he was baptized in the Holy Spirit.

We believe the baptism in the Holy Spirit with the initial physical evidence of speaking in other tongues is the promise of the Father to every Christian who desires the experience.

CONCERNS:
Pentecostals have a legitimate concern about those who oppose the baptism in the Holy Spirit. Opponents claim narrative portions of the Bible, like the Book of Acts, are not sufficient support for tongues as the initial evidence of the Baptism. But if critics can pick and choose the portions of Scripture to be given divine authenticity and authority, who then determines which portions are most meaningful? Certainly we must take to heart the words of Paul to Timothy, "All scripture is God breathed" (2 Timothy 3:16).

We also have a concern that some Pentecostals look on the Baptism and tongues as ends in themselves rather than as means to a much greater end. The Baptism is the entry experience introducing the believer to the beauty and power of the Spirit-filled life.

In the Assemblies of God we believe the Spirit is at work in all Christians, whether they have been baptized in the Spirit or not. God can also use and does use Christians who for one reason or another have not received the Baptism experience. We must never depreciate their ministry. Yet we recognize the baptism in the Holy Spirit will make one’s life and ministry even more effective.
So for every believer the command is sounded, "Be filled [Keep on being filled] with the Spirit" (Ephesians 5:18).

http://ag.org/top/Beliefs/gendoct_02_baptismhs.cfm