“Assembly” is probably the closest English word to “ekklesia”, which is commonly mistranslated as “church” in our English Bibles.
But even “assembly” falls short.
When the NT was written, “ekklesia” almost always – in the common usage of the day – referred to a participatory assembly of local citizens appointed as the governing authority, under Rome, in a city or region.
In Israel during Jesus’ time on Earth, the local ekklesia under Roman rule was the Sanhedrin.
Each city or provence had their own local ekklesia, which oversaw local affairs under Roman authority through local citizens selected by the emperor.
The internal function of each ekklesia, in their own locale, was democratic – with full participation and say by each member – just like a State assembly or town council today.
The idea of Christ building His ekklesia, therefore, was subversive to Roman ears, but fully in line with His further teachings on His Kingdom.
Unfortunately, “church” today has little to do – either as to form or function – with what “ekklesia” actually meant when the New Testament was written.
To really understand the Bible, we need to learn what it actually said when written, based on the meaning and context of the words used, rather than reading back into those words our conflicting post-New Testament meanings.