John Ritenbough explains it like this:
Matthew 16:18, the word
Jesus used for "church" is
ekklesia (
Strong's #1577), and it is so translated in the King James Version 115 times.
This Greek word means "an assembly" or "a group of people called together for a purpose." It contains no implication at all of sacredness or
holiness."
However, in the Bible the word "church"
never refers to a building or to worship services held within the building. It
always refers to the assembly, group, or congregation of called-out ones who belong to the Lord, worship Him, and fellowship with others of the same mind."
https://www.theberean.org/index.cfm/fuseaction/Home.showBerean/BereanID/8472/Matthew-16-18.htm
Can it be argued that church services follows the Biblical Sabbath? Doesn't your average church contain engraven images and display pagan symbology? Doesn't your average church ask you for tithes in the form of money? Doesn't the aversge church have self-annointed preachers and pastors leading service? All of that goes against the Most Highs commandments so surely this can't be what Matthew is referring to.
The seven churches of Asia are seven called out groups of people who serve the Most High together.