What word could be more consumately Jewish than "synagogue?" When most people think of synagogues, they think of the buildings where Jews have formally gathered for prayer and the reading and exposition of the scriptures since the time of the Babylonian exile. Yet the word synagogue itself has Greek and not Jewish origins. The actual Greek word from which we get synagogue is sunago meaning "to bring or gather together." So, for instance, in Matthew 2:4 after King Herod (who was an Idumaean, not a a Jew) receives a delegation of wise men from the east who have come seeking "He who has been born King of the Jews" so that they may "worship Him" (Matt. 2:2) we read that Herod was "troubled" and "gathered together" all the chief priests and scribes of the people. This gathering is described using the same word translated "synagogue" elsewhere, and while they quote scripture to Herod, it clearly isn't a worship service that is being held in a building designed for religious services. As a matter of fact, the objective of "Herod's Synagogue" is not to worship the Messiah, but to find and kill Him! (Matt. 2:16)
Therefore, the word "synagogue" doesn't really refer to the building, but the assembly of people who gather together to worship in it. This has enormous importance to understanding other words like "church," which is the English translation for the Greek word, ekklesia. Ekklesia means "assembly" and once again does not refer to the building that the people gather in, but the people who have been gathered together. The Greek word ekklesia was the word that the Jewish translators of the Old Testament into Greek chose to use for the Hebrew word qahal meaning the "congregation" of the Lord.
So when we look in the bible we see that "gathering together" has always been a vital part of the definition of what it means to be a worshipper of the Lord. They are literally known as the ones who have been "gathered together" by the Lord. If we understand this, it will help us to understand that when Christ says in Matthew 16:18b "I will build My church (ekklesia), and the gates of Hades shall not prevail against it" that Jesus is not talking about a hierarchy, a building or autonomous individuals but a congregation, an assembly of worshippers whom not even Hell will be able to stop. And if we understand that, then we will also understand why, as members of that congregation, we must heed the advice of Hebrews 10:25 -"Not forsaking the assembling of ourselves together, as the manner of some is; but exhorting one another: and so much the more, as ye see the day approaching."