We often tend to think that in the time before the life of Jesus, God was working exclusively with the nation of Israel, and in the time since he works mostly with Gentile believers. This may be generally true. Paul expresses in Ephesians 3 the mystery that was not made known in earlier times. “This mystery is that through the gospel the Gentiles are heirs together with Israel, members together of one body, and sharers together in the promise in Christ Jesus.” (3:6)
But this division is not nearly as clear cut as we tend to think. For one thing, the “church” has not replaced Israel in God’s working, as many like to think. This passage in Ephesians emphasizes that Gentiles who turn to God through Jesus are joined together with Israel. In Romans 11 Paul uses the metaphor of wild olive branches grafted into a cultivated olive tree to show how Gentiles become part of covenant Israel when they turn to God through Jesus.
But an interesting part of this issue is that God folding Gentiles in with Israel is not really anything new. We recall that when Israel left Egypt, they were joined by a “mixed multitude”. (Exodus 12:38) Throughout the Pentateuch instructions are given, mostly for the observance of holy days, and it is emphasized that “the same law applies to the native-born and to the alien living among you”. (Exodus 12:49 – cp. Leviticus 24:22; Numbers 15:15, 29)
We also have examples of Gentiles/foreigners who attached themselves to Israel, such as Ruth. Her passionate plea to Naomi that “your people will be my people and your God my God” ought to resonate with all Gentiles who believe in Jesus today.
Jesus also references the integration of Gentiles into Israel when he presents himself as the good shepherd in John 10. “I have other sheep that are not of this sheep pen. I must bring them also. They too will listen to my voice, and there shall be one flock and one shepherd.” (10:16)
There is a passage that’s less well-known but deals with this same theme in Isaiah 56. Here Isaiah addresses two groups of people who were considered to be somewhat out of God’s favor, foreigners and eunuchs. He gives the same message to each, a message of welcome and inclusion followed by an urging to righteous living and a sense of the reward to follow.
It’s worth noting what Isaiah records God as saying to these groups in his instruction for righteous living. We can get some sense of God’s priorities in passages like this. To the eunichs he says, “To the eunuchs who keep my Sabbaths, who choose what pleases me and hold fast to my covenant…” (56:4)
To the foreigners he says, “And foreigners who bind themselves to the LORD to serve him, to love the name of the LORD, and to worship him, all who keep the Sabbath without desecrating it and who hold fast to my covenant…” (56:6) The list to foreigners is a little longer, but both include keeping the Sabbath and holding fast to his covenant.
It’s interesting that there are verses in the immediate vicinity, both preceding and following, that address the importance in God’s eyes of keeping the Sabbath. “This is what the LORD says: ‘Maintain justice and do what is right, for my salvation is close at hand and my righteousness will soon be revealed. Blessed is the man who does this, the man who holds it fast, who keeps the Sabbath without desecrating it, and keeps his hand from doing any evil.'” (56:1-2) “If you keep your feet from breaking the Sabbath and from doing as you please on my holy day, if you call the Sabbath a delight and the LORD’s holy day honorable, and if you honor it by not going your own way and not doing as you please or speaking idle words, then you will find your joy in the LORD, and I will cause you to ride on the heights of the land and to feast on the inheritance of your father Jacob.” (58:13-14)
It is, in my view, a major tragedy that in the second century the bulk of “Christianity” turned against Israel (the Jews) and against God’s law. Admittedly it was mostly driven by the Fiscus Judaicus, an onerous tax on Jews and those who lived similarly. But in trying to distance themselves from the Jews by establishing different days of worship and festivals than the biblical ones, Gentile believers surrendered much of God’s approval and blessing.
God was fairly clear in the Hebrew scriptures which day he considered to be the Sabbath, and there is no hint of a change of day in the New Testament. “The Lord’s day” in Isaiah 58:13 is clearly the seventh-day Sabbath.
The issue among believers is not “worshiping on Sundays”. It’s a good thing to worship God on any day of the week. The problem is in not giving the regard to the seventh day that God commanded. I urge those Gentile believers in Jesus who really want to follow God’s priorities to set aside Saturday (Friday sunset until Saturday sunset) as a holy day and refrain from doing work and normal day-to-day activities. This should be done not to try to earn God’s favor, but out of love for him and obedience to his commands.