The irreducible ecclesiological minimum for a local church

What is the irreducible ecclesiological minimum for a local church? Can use ontological aspects, structural elements, functional considerations, and instrumentally in the paper. Set forth what you believe is essential, minimal, necessary for the church ontological aspects, what it means to be the local church? structural elements such as church leadership roles or organizational design functional considerations, what we do, such as worship or missions, etc. instrumentally, what is the purpose of the local church, or what does it strive to accomplish?