The historical answer for this, as it applies to Gentiles, was recorded on the book of Acts.
Mosaic Law was given to the nation of Israel (the Jews), not the Church.
Early on in Church history, the question of whether adherence to Mosaic Law was to be applied to Gentile believers.
New International Version (NIV) The Council at Jerusalem
15 Certain people came down from Judea to Antioch and were teaching
the believers: “Unless you are circumcised, according to the custom
taught by Moses, you cannot be saved.” 2 This brought Paul and
Barnabas into sharp dispute and debate with them. So Paul and Barnabas
were appointed, along with some other believers, to go up to Jerusalem
to see the apostles and elders about this question. 3 The church sent
them on their way, and as they traveled through Phoenicia and Samaria,
they told how the Gentiles had been converted. This news made all the
believers very glad. 4 When they came to Jerusalem, they were welcomed
by the church and the apostles and elders, to whom they reported
everything God had done through them.
5 Then some of the believers who belonged to the party of the
Pharisees stood up and said, “The Gentiles must be circumcised and
required to keep the law of Moses.”
6 The apostles and elders met to consider this question. 7 After much
discussion, Peter got up and addressed them: “Brothers, you know that
some time ago God made a choice among you that the Gentiles might hear
from my lips the message of the gospel and believe. 8 God, who knows
the heart, showed that he accepted them by giving the Holy Spirit to
them, just as he did to us. 9 He did not discriminate between us and
them, for he purified their hearts by faith. 10 Now then, why do you
try to test God by putting on the necks of Gentiles a yoke that
neither we nor our ancestors have been able to bear? 11 No! We believe
it is through the grace of our Lord Jesus that we are saved, just as
12 The whole assembly became silent as they listened to Barnabas and
Paul telling about the signs and wonders God had done among the
Gentiles through them. 13 When they finished, James spoke up.
“Brothers,” he said, “listen to me. 14 Simon[a] has described to us
how God first intervened to choose a people for his name from the
Gentiles. 15 The words of the prophets are in agreement with this, as
it is written:
16 “‘After this I will return
and rebuild David’s fallen tent. Its ruins I will rebuild,
and I will restore it, 17 that the rest of mankind may seek the Lord,
even all the Gentiles who bear my name, says the Lord, who does these things’[b]— 18 things known from long ago.[c]
19 “It is my judgment, therefore, that we should not make it difficult
for the Gentiles who are turning to God. 20 Instead we should write to
them, telling them to abstain from food polluted by idols, from sexual
immorality, from the meat of strangled animals and from blood. 21 For
the law of Moses has been preached in every city from the earliest
times and is read in the synagogues on every Sabbath.”
More is available at Grace Communion International.
Why, then, these four rules? Some scholars say the Jews believed that
these laws dated back to the time of Noah, and therefore applied to
all nations. Others say that all four rules were associated with
idolatry. Some say that these four rules were laws of Moses, and were
given so Gentiles and Jews could eat together. None of these
suggestions is fully convincing. (See later for more details.)
However, the decree makes it clear that Gentiles do not have to be
circumcised, nor do they have to obey the laws of Moses. They are
circumcised spiritually, not physically. God never gave those commands
to the Gentiles.
To summarize: Some men said that Gentiles should be circumcised and
obey the laws of Moses or else they could not be saved. Not so, said
the apostles. Gentiles are saved by grace and faith. God is pleased to
dwell in people who aren’t circumcised and who don’t keep the rituals.
But since Moses is widely preached, we need to give a decree that
clearly distinguishes the Christian faith from the Law of Moses. This
pleased the entire church, so they wrote it in a letter and sent it to
Antioch, where they “were glad for its encouraging message”