Matthew is thought to be written to Christians who were culturally Jewish. Some reasons for this are that the text frequently quotes Old Testament prophecies that the culturally Jewish would have been familiar with and that the text makes comparisons between Jesus and Moses (e.g. survived infanticide, 40 days in the wilderness, lower vs higher law, Mount of Transfiguration). Another reason scholars think that Matthew was written to the culturally Jewish is that the Book of Matthew highlights gentile righteousness, or the goodness of the people who were notGod’s chosen people.
I am no expert on Jewish history or traditions, but one thing I do know is that the ancient Jews felt purposefully different from those around them. In fact, in Hebrew the word holy (kadosh) means to be set apart from what is around you. They kept laws that, when you think about it, have little purpose other than to make them different: they circumcised their male born children as a sign of the law, they only did certain activities on the Sabbath day (to keep it holy), and they kept kosher (dietary restrictions) among other things. For millennia, Jews viewed those with different faith traditions as heathens, and young men were told not to marry those from other cultures, “You shall not marry one of the Canaanite women.” (Gen. 28:6).
So, why would a book written for Jews highlight the faithfulness of gentiles? To understand this, we need to know some of the political context surrounding the writing of Matthew. In the decades after the crucifixion, there were two main types of Christians: those who were culturally Jewish (like Peter and the original disciples) and those who were not, or gentiles who had converted to Christianity (like Cornelius or Titus). Most scholars agree that Matthew was probably written around 80 CE by a community in Antioch that was founded by culturally Jewish Christians, but which had a large gentile Christian population.
At some point in early Christianity, God instructed that the “good news” was not just for the Jews, but that it was for gentiles too. Unsurprisingly, it is the book of Matthew where Jesus instructs the disciples, “Go therefore and make disciples of all nations.” (Matt. 28:19, emphasis added). But, one question that God did not answer is how the gentiles should convert to Christianity. Many Jews felt, naturally, that keeping Jewish law was an absolute must for any Christian. After all, they had been keeping Jewish law for millennia. Others, most notably Paul the great missionary, felt that it was not necessary for gentiles to essentially convert to Judaism before they converted to Christianity, “We ourselves are Jews by birth and not Gentile sinners; yet we know that a person is justified not by the works of the law but through faith in Jesus Christ.” (Galatians 2:15-16).
There is so much to be said about this debate, but to summarize, in 49 CE the leaders met and decided that it was not necessary for gentiles to follow Jewish custom (see Acts 15 and Galatians 2). But, as we know, it takes people some time to get used to new ideas. Many culturally Jewish Christians considered gentiles to be second-class-citizens because they did not follow their traditional customs; there was tension and division between the two types of Christians because there were Jews who would not accept the new truth.
For this reason, scholars think that the passages that highlight gentile faithfulness (many unique to Matthew), are meant to teach the culturally Jewish Christians who look down on gentile converts that it is wrong to think that you are better because you follow a set of traditions. Matthew teaches its readers to look beyond cultural differences (or dare I say – lifestyles) and to instead focus on those things that we have in common.