Oh, Those Atheist Mega Churches!
There is an organization named "Man Will Never Fly"! I have never protested that organization because for one thing - My Dad was a Pilot for a Major Airline! Secondly, I personally have 2 million Frequent Flyer Miles with Delta Air Lines!
So why do these people who don't believe in God feel a need to meet on Sundays? The answer is quite simple! God created a hole in our hearts that must be filled with something! The best thing that we can add to our hearts is the One True God of the Bible who loves us so much that He sent His Son to die for us! Others choose false religions but most prefer to just fill that void with themselves & their own idols - whatever they might be.
Usually people create idols out of good things such as personal achievements, social status or even family!
My guess is that these people enjoy their own personal sins to much & refuse to accept the Savior's offer for forgiveness & must simply fabricate their own way!
By the way - these atheist meetings don't even come close to a real Mega-Church where thousands meet. Check out the video below & note the size crowds at a BG Meeting:
Here's a much better avenue for filling the void in our hearts that only Jesus Christ can fill: Excitement, Love & True Happiness!