The first Christians were Jews and they worshipped the God of Abraham as their ancestors had done. Apostolic Christianity was nothing more that the religion of Judaism baptized into Christ. After having accepted Christ the Jewish Christians continued to practice the forms and rituals of their ancient faith. In those days there was no conflict between being a practicing Jew and a Christian at the same time.
Proof that many of the early Christians remained practicing Jews in found in Acts 21:20 which reads, “You see, brother, how many thousands there are among the Jews of those who have believed. They are all zealous for the law.” In Apostolic Christianity being a Christian and a Jew was an acceptable norm.
It was Paul who was the first to see that the rituals of Judaism were precipitators of coming events. As he saw it, Jewish rituals did not exist for their own sake but were at their center prophetic pointers to Christ. The rituals proclaimed that one-day the Messiah would come and when Christ did come the rituals had no role to play as prophetic indicators of a future hope because that hope had already arrived with Christ.
Paul declared that the Law of Moses with its many prescriptions for worship “was our guardian until Christ came, … but now that faith has come we are no longer under a guardian.” (Galatians 3:24) The “guardian” in this context is the whole Law of Moses as a manual for directing old covenant worship. Saying "we are no longer under a guardian" means we are no longer under Moses Law.
In devaluing Jewish rituals Paul was not denigrating the Ten Commandments. God's moral requirements are free of ethnic limitations in all times and places, besides which before God there is no such thing as an exclusively "Jewish" moral law.
For Paul the practice of the signs and symbols of Judaism beyond the coming of Christ has no validity at all. There is both passion and unmistakable clarity in these words: “Behold, I Paul say unto you, that if ye be circumcised, Christ shall profit you nothing.” (Galatians 5:2)
Paul explained to the Galatians that it is not necessary to be Jewish in order to be a Christian. A large body of the Jewish Christians, and possibly the majority located in Jerusalem were saying the opposite. “But some men came down from Judea and were teaching the brothers, "Unless you are circumcised according to the custom of Moses, you cannot be saved. And Paul and Barnabas had no small dissension and debate with them.” (Acts 15:1,2)
It needs to be emphasized that Paul did not oppose Jewish Christians who continued to practice Jewish rituals; he only opposed the Jewish Christians who taught that it was necessary to practice certain rituals, without which according to them, “you cannot be saved.”
It is true Paul maintained his Jewish identify but Paul himself says that this was only for evangelical purposes, not out of necessity. He writes: “To the Jews I became as a Jew, in order to win Jews. To those under the law I became as one under the law (though not being myself under the law) that I might win those under the law.” (1 Corinthians 9:20)
Paul's statement “though not being myself under the law” shows he did not believe the observance of the Law of Moses was compulsory, even for a Christian brought up in Judaism.
Paul's position of non-compulsory compliance to the Law of Moses was very much a minority opinion among the Christian Jews. A Council was called in Jerusalem to settle the matter and we can read about it in Acts 15. The fundamental issue is identified in verse 5. “But some believers who belonged to the party of the Pharisees rose up and said, it is necessary to circumcise them and to ORDER them to keep the Law of Moses.”
Because Acts 15:5 tells us it was “the Pharisees” who started the debate we can be sure the controversy was not limited to circumcision but involved the compulsory observance of “the Law of Moses” in total. This means the discussion would have focused on sacrificial offerings and the observance of days as well as circumcision. The issue was not whether it was permissible for a Jewish Christians to observe the Law of Moses but whether or not observing the law of Moses was a compulsive requirement for anyone professing faith in Christ.
The first Christian Council involved a debate called to clarify the requirements of the new covenant based on faith in Christ. After some heated discussion with a few minor exceptions the findings of the Council came out in support of Paul. In a few simple words the Councils deliberation stated,
“For it has seemed good to the Holy Spirit and to us to lay on you no greater burden than these requirements: that you abstain from what has been sacrificed to idols, and from blood, and from what has been strangled, and from sexual immorality. If you keep yourselves from these, you will do well.” (Acts 15:28-29)
The judgment of the Council virtually obliterated all of the demands of the Pharisees' concerning the Law of Moses. And because Scripture itself says that the requirements imposed by the Council that excluded the Pharisees' demands “seemed good to the Holy Spirit” there is clearly no obligation for a Christian to observe circumcision, sacrificial offerings, or any monthly or annual festival that the Pharisees demanded and which the Jerusalem Council rejected. But there is no prohibition against anyone treating these festivals as memorials of faith either. What is wrong is when people attempt “to ORDER them to keep the Law of Moses.” (Acts 15:5)
The fact is, whereas the spring festivals in the law of Moses pointed to events associated with Christ's first coming the autumn festivals focus on events connected to His second coming, so they have not been fulfilled yet. If their eschatological meanings have not yet been realized then in biblical terms these festivals even today remain proto types of that which is still to come.
In answer to what has become a controversial question: "Should Christians observe Old Testament festivals?" We need to remind ourselves that the Jerusalem Council under the guidance of the Spirit rejected the Pharisees demand that "it is necessary to ... ORDER them to keep the Law of Moses." In reference to the question of Christians observing Jewish festivals Paul wrote,
“One person esteems one day as better than another, while another esteems all days alike. Each one should be fully convinced in his own mind.” (Romans 14:5) The maintenance of free choice in this matter is the essence of religious liberty.