I am resisting the urge to launch into a look at the doctrinal considerations that should serve as primary factors when deciding on a church. For now, let's consider the numbers. What does the bible have to say about numbers as they relate to following the will of God? Does the majority generally operate within the will of God? When it comes to salvation we cannot say that the majority has it right. Read the words of Jesus.
"Enter through the narrow gate; for the gate is wide and the way is broad that leads to destruction, and there are many who enter through it. For the gate is small and the way is narrow that leads to life, and there are few who find it." (Matthew 7:13-14)
Look at the numbers in this passage. "Many" are headed to destruction and "few" are those who choose wisely. Is this a situation in which you want to go with the numbers and follow the crowd? Is there safety in numbers? No, there is destruction for the vast majority.
Now you may be saying, "but mega churches are made up of believers." Maybe, maybe not, but again, staying away from the doctinal issues what about the numbers? Is there a guarantee of safty in numbers of believers? Read the words of Jesus just a few verses later in Matthew 7.
"Not everyone who says to Me, 'Lord, Lord,' will enter the kingdom of heaven, but he who does the will of My Father who is in heaven will enter. Many will say to Me on that day, 'Lord, Lord, did we not prophesy in Your name, and in Your name cast out demons, and in Your name perform many miracles?' And then I will declare to them, 'I never knew you; DEPART FROM ME, YOU WHO PRACTICE LAWLESSNESS.'" (Matthew 7:21-23)
When considered together, these two passages are nothing short of alarming. From verses 13-14 we learn that "few" avoid destruction and from verses 21-23 we learn that "many" who worshiped the Lord are doomed to hell. Dare I say that "many" people who believed in the Lord are doomed to hell. Obviously something went wrong with their doctrine for them to believe in the Lord, worship the Lord, and then not enter the eternal kingdom of God. Are we assured of safey in numbers of believers? Can "many" believers be wrong? I'm not suggesting that those who attend mega churches are doomed to hell. The point is, don't base your decision regarding which church to attend on numbers. This decision must be made under direction of the Holy Spirit who will guide you to a church that teaches sound doctrine.
One last look at the numbers and in this case let us consider lower numbers. What about those smaller churches that do not have the high membership numbers? Is lower membership numbers a reflection of poor teaching and false doctrine? Could the Lord be leading you to a smaller church? Read this verse from Luke.
"For the one who is least among all of you, this is the one who is great." (Luke 9:48b)
Does this sound like a popular, mega church goer? The "least" is called "the one who is great" and "great" is not a reference to numbers. "Great" is a reference to the believer who stays true to sound doctrine and glorifies God. The "least" among us are those who are barely noticeable. The "least" are the humble. You will hardly know they are there as they give the Lord all the glory and seek none for themselves. George Whitefield said, "Let my name die everywhere, let even my friends forget me, if by that means the cause of the blessed Jesus may be promoted." That is humility. That is greatness. That has nothing to do with numbers.