Matt 24:24-25 For false christs and false prophets will rise and show great signs and wonders to deceive, if possible, even the elect. 25 See, I have told you beforehand.
Back years ago, I heard a well known salesman that regularly competed with the number one company in his industry. Those competing against him from the big company would regularly tout how big they were and how small his company was. His response still makes me laugh: "If size were everything, elephants would rule the world and Miss America would weigh 400 pounds!" So, then, size is not necessarily a proof of the working of God in a church.