Acts 18:18 Updated American Standard Version (UASV)
¹⁸ After this, Paul stayed many days longer and then took leave of the brothers and set sail for Syria, and with him Priscilla and Aquila. At Cenchreae he had cut his hair, for he was under a vow.

Edward D. Andrews writes,

Scholars have hotly debated this vow that Paul had taken for hundreds of years, some suggesting that Paul had taken a Nazirite vow. (Num. 6:1-21) So, let’s look at a few commentators before addressing the issue ourselves.

 Barnhouse writes,

Here, Paul was definitely out of the will of the Lord. He had no right to take this vow, or to have his head shaved as a symbol of it. This was deliberate sin on his part. Since God puts everything in Scripture, I believe he allows us to see this episode so that we can realize that Paul was fallible in some things (Barnhouse, 168–169).[1]

Polhill says:

In any event, the significance of the vow is that it shows Paul to have been a loyal, practicing Jew. In his mission to the Gentiles, he did not abandon his own Jewishness. He was still a “Jew to the Jews” and still continued his witness in the synagogues. Interestingly, on Paul’s final visit to Jerusalem, when James wanted him to demonstrate his Jewish loyalty before the more legally zealous Jewish Christians, participation in a similar vow was chosen as the means to accomplish this (21:20–24).[2]

F. F. Bruce writes,

Before setting sail, he had his hair cut: he had allowed it to grow long for the duration of a vow which he had undertaken. This was probably not a formal Nazirite vow, which could not properly be undertaken outside the Holy Land,[3] but a private vow, the fulfilment of which was an act of thanksgiving—possibly for the divine promise of verse 10, which had been confirmed by his preservation from harm throughout his Corinthian ministry.[4]

Simon J. Kistemaker and William Hendriksen wrote,

“[Paul] had his hair cut in Cenchrea, for he was keeping a vow.” Although the Greek word order can mean that Aquila had made a vow, the context points to Paul as the main subject in this verse. Paul followed the Jewish practice of making a Nazirite vow which stipulated that a person cut his hair at the conclusion of a specified period. Within thirty days following this period, a sacrifice had to be offered in Jerusalem. After Paul had made his vow, he was obligated to travel to Jerusalem and offer his locks with the sacrifice.³⁶ Paul made this vow to express his thanksgiving to God for protecting him in Corinth and for blessing his work. To the Jews, Paul remained a Jew even in keeping vows and bringing offerings to the temple (21:23–26).[5]

However, the Bible what Paul’s vow was is not stated. The more important point to consider is, we do not know whether the vow was made before or after Paul was converted. Or another point to consider is that we do not know if he had already started the vow and was now ending the vow. Regardless, Barnhouse mentioned below is mistaken and taking a vow was not sinful. Was this related to what took place later in Jerusalem?

Paul was in Jerusalem after his third missionary journey. The Christians leaders revealed that there was a tremendous amount of bitterness and dislike among the Jews toward Paul. There were allegations which the Jews believed that Paul was zealously preaching to be disobedient to the Mosaic law. This was actually true, in that Paul preaching that the Law was removed by the ransom sacrifice of Jesus Christ. James and the older men instructed Paul: “Therefore do this that we tell you. We have four men who have a vow upon themselves; take them and purify yourself along with them and pay their expenses so that they may shave their heads; and all will know that there is nothing to the things which they have been told about you, but that you yourself also walk orderly, keeping the Law.”—Acts 21:23-24.

It was normal among the Jews for a wealthy person to help with the expenses engaged in the ceremonial cleansing at the conclusion of the period of a vow, which is what Paul was doing here. (Acts 21:26) This was not some traitorous act  by Paul and those Christian leaders in Jerusalem. They showed that the Jewish laws concerning vows had not become wicked simply because Christians were not obligated follow them. What they did was not inappropriate, and it would lessen Jewish biases, which would then allow many to hear accept the gospel message that Paul was passionately intent in preaching.

There are some things that need to be considered as to why Paul and the Christian leaders were fine with some aspects of the Law, although the Mosaic Law had been removed by the sacrifice of Jesus Christ. This was no pagan Law; it was given by God himself to the Israelite people. On this Paul wrote, “So then, the Law is holy, and the commandment is holy and righteous and good.  For we know that the Law is spiritual, but I am of the flesh, sold under sin.” (Rom. 7:12, 14) Therefore, the temple services were not despised by Christians, or viewed as wrong. It was not idolatrous. Additionally, many of these practices in and of themselves had been a way of life among the Jewish people for 1,600 years. They were accustomed to carrying out these practices because they were ingrained in them. We must also remember that Israel was a theocrasy for of government. It was the law of the Israel and religious at the same time. So, some parts of the Mosaic Law had to be followed, like the Sabbath, if one was going to live in the land.

The difference between the Jewish people and the Jewish and non-Jewish Christians is that the Jews looked to the Mosaic Law as a means to gaining salvation and the Christians did not. Paul wrote, “One person esteems one day above another, while another esteems all days alike. Each one should be fully convinced in his own mind. The one who observes the day, observes it in honor of the Lord. The one who eats, eats in honor of the Lord, since he gives thanks to God, while the one who abstains, abstains in honor of the Lord and gives thanks to God. For the kingdom of God is not eating and drinking, but righteousness and peace and joy in the Holy Spirit. The faith that you have, keep it to yourself before God. Blessed is the man who does not judge himself by what he approves. But the one who doubts is condemned if he eats, because he does not do so from faith; and whatever is not from faith is sin.” – Romans 14:5-6, 17, 22-23.

Elsewhere, Paul writes,

1 Corinthians 10:25-30 Updated American Standard Version (UASV)
²⁵ Eat whatever is sold in the meat market without raising questions for the sake of conscience. ²⁶ For “the earth is the Lord’s, and the fullness thereof.” ²⁷ If an unbeliever invites you and you want to go, eat whatever is set before you, asking no questions for the sake of your conscience. ²⁸ But if someone says to you, “This is meat sacrificed to idols,” do not eat it, for the sake of the one who informed you, and for conscience’ sake. ²⁹ I do not mean your own conscience, but that of the other person. For why should my freedom be judged by another person’s conscience? ³⁰ If I partake with thankfulness, why am I slandered concerning that for which I give thanks?

So, the point here that Paul is making is that some things like eating meat, esteeming one day above another, eating meat that had even been offered to idols before being put on sale in the market was a conscience decision.

An instructive comment is made concerning this point in Acts 21:20, “they are all zealous for the Law,” by Bible scholar Albert Barnes, “It may seem remarkable that they should still continue to observe those rites, since it was the manifest design of Christianity to abolish them. But we are to remember, (1) That those rites had been appointed by God, and that they were trained to their observance. (2) That the apostles conformed to them while they remained at Jerusalem and did not deem it best to set themselves violently against them, ch. 3:1; Lu. 24:53. (3) That the question about their observance had never been agitated at Jerusalem. It was only among the Gentile converts that the question had risen, and there it must arise, for if they were to be observed, they must have been imposed upon them by authority. (4) The decision of the council (ch. 15) related only to the Gentile converts. It did not touch the question whether those rites were to be observed by the Jewish converts. (5) It was to be presumed that as the Christian religion became better understood—that as its large, free, and catholic nature became more and more developed, the peculiar institutions of Moses would be laid aside of course, without agitation and without tumult. Had the question been agitated at Jerusalem, it would have excited tenfold opposition to Christianity, and would have rent the Christian church into factions, and greatly retarded the advance of the Christian doctrine. We are to remember also, (6) That, in the arrangement of divine Providence, the time was drawing near which was to destroy the temple, the city, and the nation, which was to put an end to sacrifices, and effectually to close forever the observance of the Mosaic rites. As this destruction was so near, and as it would be so effectual an argument against the observance of the Mosaic rites, the Great Head of the church did not suffer the question of their obligation to be needlessly agitated among the disciples at Jerusalem.”[6]

SCROLL THROUGH THE DIFFERENT CATEGORIES BELOW

BIBLE TRANSLATION AND TEXTUAL CRITICISM

BIBLICAL STUDIES / INTERPRETATION

EARLY CHRISTIANITY

CHRISTIAN APOLOGETIC EVANGELISM

TECHNOLOGY AND THE CHRISTIAN

CHRISTIAN THEOLOGY

CHRISTIAN DEVOTIONALS

CHRISTIAN FICTION

[1] Donald Grey Barnhouse, Acts: An Expositional Commentary Grand Rapids, MI: Zondervan, 1982), 168-169.

[2] John B. Polhill, Acts, vol. 26, The New American Commentary (Nashville: Broadman & Holman Publishers, 1992), 390.

[3] If the vow was made in another country, its fulfillment required a residence of at least thirty days in Judaea, and at the end of that time the hair would be shorn and offered in the temple (cf. Num. 6:18). The vow mentioned in 21:23–26 below was a real Nazirite vow (see the Mishnaic tractate Nāzîr). It is grammatically possible to make Aquila the subject of the following verbs, but “the natural emphasis marks Paul as the subject here” (Ramsay, St. Paul the Traveller, p. 263).

[4] F. F. Bruce, The Book of the Acts, The New International Commentary on the New Testament (Grand Rapids, MI: Wm. B. Eerdmans Publishing Co., 1988), 355.

[5] Simon J. Kistemaker and William Hendriksen, Exposition of the Acts of the Apostles, vol. 17, New Testament Commentary (Grand Rapids: Baker Book House, 1953–2001), 663.

[6] Albert Barnes, Notes on the New Testament: Acts, ed. Robert Frew (London: Blackie & Son, 1884–1885), 306.