The Mosaic Laws were given to the Jews. Gentile believers were observed receiving the Holy Spirit without observing the Mosaic Law. It became apparent to the Apostles that they needed to hear from the Holy Spirit and arrive at a consensus on which portions of the Mosaic Law Gentile believers are instructed to comply with. Their final decision on this matter was made in the letter sent to the Gentiles in Acts 15:23-29, which is termed the Jerusalem Decree.
Acts 15:23 They wrote this letter by them:
The apostles, the elders, and the brethren,
To the brethren who are of the Gentiles in Antioch, Syria, and Cilicia:
Greetings.
24 Since we have heard that some who went out from us have troubled you with words, unsettling your souls, saying, “You must be circumcised and keep the law”—to whom we gave no such commandment— 25 it seemed good to us, being assembled with one accord, to send chosen men to you with our beloved Barnabas and Paul, 26 men who have risked their lives for the name of our Lord Jesus Christ. 27 We have therefore sent Judas and Silas, who will also report the same things by word of mouth. 28 For it seemed good to the Holy Spirit, and to us, to lay upon you no greater burden than these necessary things: 29 that you abstain from things offered to idols, from blood, from things strangled, and from sexual immorality. If you keep yourselves from these, you will do well.
Farewell.
Some say that taking the Jerusalem Decree literally leads to lawlessness. To which I say Jesus commanded his disciples to keep His commandments (
John 14:15), not the Mosaic Law. We are all to keep Jesus's commandments.
Years after the Jerusalem Decree, Paul reiterates the portions of the Mosaic Law the Gentiles are to keep and nothing has changed - thus confirming the decision.
Acts 21:24 Take them and be purified with them, and pay their expenses so that they may shave their heads, and that all may know that those things of which they were informed concerning you are nothing, but that you yourself also walk orderly and keep the law. 25 But concerning the Gentiles who believe, we have written and decided that they should observe no such thing, except that they should keep themselves from things offered to idols, from blood, from things strangled, and from sexual immorality.”
And a warning from Paul.
Titus 3:9 But avoid foolish controversies and genealogies and arguments and quarrels about the law, because these are unprofitable and useless.