The Holy Spirit
"And Peter said unto them, Repent ye, and be baptized every one of you in the name of Jesus Christ unto the remission of your sins; and ye shall receive the gift of the Holy Spirit." Acts 2:38
There is probably no more controversial subject in religion than the role of the Holy Spirit in daily life. In the above scripture, quite often the question is "What is the gift of the Holy Spirit"
First I would like to deal with the question from a "true believer's" viewpoint.
The Holy Spirit was given to the apostles to guide them into all truth.
"John 16:13 "Howbeit when he, the Spirit of truth, is come, he shall guide you into all the truth: for he shall not speak from himself; but what things soever he shall hear, these shall he speak: and he shall declare unto you the things that are to come." (ASV)
We see from John 17:17 that the word of God is the truth. ("Sanctify them in the truth: thy word is truth.")
So the word of God and "the truth" when referring to God's word, are synonymous.
Other words are used that refer to the word of God, such as; the gospel, (Rom. 1:16) the teaching of Christ, the doctrine of Christ.(2nd John 9) The mission of the Holy Spirit is to declare all truth, reveal it, speak it, etc.. The only difference between the work of the Holy Spirit in John's day and today is that, today it is written. There is no more direct operation of the Holy Spirit. In apostolic days, the Word was not fully revealed, so some direct activity was needed to prove that it was the word of God.
After all, why should anyone believe one who claimed to be God's messenger, if he had no proof. So first of all, it needed to be revealed, taught and then confirmed through signs, wonders and miracles. So the Holy Spirit gave miraculous gifts to men until such time as the revealing was complete. When His earthly mission was completed, (fully revealed and confirmed) and all was recorded for our learning and obeying, there was no further need of an earthly presence, just like when Jesus mission was completed, He took His place on the throne with the Father. The Holy Spirit does not work separate and apart from man's will. The holy Spirit's work (the word, gospel, teaching) is to be preached, so that men will know how to please God and get to heaven when they die. "The word is nigh thee, in thy mouth, and in thy heart: that is, the word of faith, which we preach:" (Rom. 10:8)
Some Bible terminology is a bit confusing, but we must remember to apply sound principles of interpretation. One of the most important is never overturn the meaning of a passage that is clearly understood with one that is difficult or seems to be ambiguous. This is frequently done with references to the Holy Spirit.
Having an understanding of the role and mission of the Holy Spirit shows us what is the "gift of the Holy Spirit" It is that which completes His mission. It is the revealing of the plan of salvation. That is done by the gospel as we again state... Rom. 1:16 "For I am not ashamed of the gospel: for it is the power of God unto salvation to every one that believeth; to the Jew first, and also to the Greek."
The Holy Spirit works in us when we read it, study it, reach an understanding of it and obey it. As we do so, we draw closer to God and His Spirit. We come to know Him, as we make Him the dominant part of our lives. "O the depth of the riches both of the wisdom and the knowledge of God! how unsearchable are his judgments, and his ways past tracing out!" (Rom. 11:33)
This does not mean we cannot attain to a knowledge of God. It means that His word will provide us with all we need to grow in Godly wisdom and study of it is never complete. However, as we continue to study and meditate we will grow in ways that are above our pay grade. (so to speak) "that he would grant you, according to the riches of his glory, that ye may be strengthened with power through his Spirit in the inward man;" It is our spirit that grows beyond measure when our faith grows beyond measure... "That Christ may dwell in your hearts through faith; to the end that ye, being rooted and grounded in love, may be strong to apprehend with all the saints what is the breadth and length and height and depth, and to know the love of Christ which passeth knowledge, that ye may be filled unto all the fulness of God. (Eph. 3:16-19) So how does Christ dwell in our hearts?... "through faith"...not miraculously or mysteriously. When the Psalmist said "my cup runneth over", he was not speaking of mere material blessings, but those riches one accumulates while seeking the heavenly kingdom. They do escape our being able to describe them, but they are filling and completely satisfying as we might expect Godly sustenance to be.