No, you don't have to be, but it's not a simple process to become a mason. If anyone here were to ever consider becoming one, I'd suggest really steping it up wherever you can. Volunteer often and for good causes, work hard at your job, be a good father, son, etc... Basically try to be an outstanding member of society. If you're a major douchebag, doing sketchy stuff, anything questionable, then I think your chances of becoming a Freemason drop drastically.
I'm pretty sure the whole process of becoming a mason (there are a few in the family and I come from a line of em so I'm basing this off of the knowledge I've gained over the years) goes something like a so:
1.Petition the lodge; basically you ask for a questionairre from the lodge. Gotta fill this puppy out super truthfully. Then it has to be signed by a current member of the lodge.
2.The lodge investigates the petitioner: Appointed members from the lodge will meet with you, could be one on one, could be as a group, could be at the lodge, could be at your house, could be at a public place. Sort of like a job interview I guess, and also a continuation of the petition in a way...
3.The lodge will then vote on the candidate and I think it has to be unanimous. So if one person says no, then you're toast. But I wouldn't be super worried about a biased voter or anything along those lines, afterall, the voters in this case are Masons, so obviously they are pretty truthful, honest people.
4. If you're accepted then you have to do some levels of something, not sure of what but you have to be proficient with them when your done. I think there are 3 or 4. You'll likely have to work along side a current member of the lodge to become proficient at them to. Once you've proved your proficiency then you're a full member. Then there are more optional degree's/levels after that but they're optional.
Wow that's a wall of text right there. I'll see if I can post a pic of my great grandpa's Masonic necklace thing sometime. It's super cool. It's like a ball that basically opens up in to 6 separate pyramids that lay out in the shape of a cross, then has all-seeing eyes engraved in the faces of the pyramids and other symbolism. Mega cool.