Denver will play host to the largest marijuana convention in the U.S. this weekend.The cannabis convention will be held at the Colorado Convention Center starting Friday at 4 p.m. It continues Saturday at 10 a.m.Organizers say it could be the largest marijuana convention in the nation's history.I'm really excited, said Michael Lerner, owner and publisher of Kush magazine. We have a doctor's panel, a legal panel - with some of the top attorneys in the state.The marquee outside the convention center says Reefer Mania. Denver's Gone To Pot.But not everyone is that enthusiastic about it.Medical marijuana is a fraud. That you have to keep a dispensary thousands of feet away from a school proves that it's not medicine, said Pastor Bob Enyart.Donovan O'Dell disagrees.Its been a blessing. I put that on and in a few minutes the pain was gone, said ODell.He uses a topical marijuana to control a painful condition, like Shingles, on his skin.So, technically, as we speak I'm under the influence of medical marijuana. The influence is: I don't feel pain, said ODell.Whatever the influences - the convention promises to be big. Some promoters estimate it could attract the largest crowd the convention center has ever seen.It is helping people. And healing people, said Lerner.It's wrong to lose control of your faculties. You become a burden to society, said Enyart.The largest crowd to ever attend an event at the convention center was 53,000 at the beer festival a few years ago.Unlike the beer festival -- where there was plenty of beer -- there will be no marijuana on the premises for this event.It is strictly prohibited and there won't be any alcohol sales, either.The event is open to the public. All ages are welcome.Medical marijuana has become a hot topic in Colorado in the last year. The Colorado Department of Public Health and Environment reported that 1,000 applications for medical marijuana are being received each workday.Denver received 235 applications for marijuana dispensaries earlier this month, under a new city deadline to register as a dispensary.