yes, you can be Christian and be a Freemason. Just like how Buddhists, Muslims, Jewish, Shintoists, Hare Krishnas, Satanists, etc, can all be Freemasons too.
Its not a religion, and its not an organization exclusive to one single religion. Its a club, just like any Fraternity, Sorority, etc. Its the same as organizations like Kiwanis, Opptimist, Soroppotimist, Lions Club, Rotary, Shriners, the Frternal Order of the Elk, et al. For the most part their activities include charities, fund raisers, and community-centered events.
The symbolism behind all of their ritualistic endeavors is the smallest part of their agenda; for the most part, they're more concerned with things like volunteering for youth soccer coach, bringing the cookies and coffee this week, and financing the middle school so they can afford those new computers.
It kind of hurts me when people say Freemasons are evil, but yet, we can see the direct good they do in our communities, while those shouting "its evil!" are doing little or nothing for their own communities, yet, somehow, some people are listening to them for advice on subjects they know little or nothing about.