Technically, Belize does have this six-month requirement, though as a practical matter as long as the passport is valid for the amount of time you are planning on staying, you probably won't have a problem from Belize immigration. Airlines, however, may be stickier about enforcing this rule, as they don't want to have to ship someone back if denied entry.
To be safe, I'd have the passport renewed.
Belize books and publications by Lan Sluder:
Belize First Magazine (http://www.belizefirst.com
Fodor's Belize & Guatemala Guide (new 4th edition coming this summer)
Adapter Kit: Belize (the first and only comprehensive guide to living, retiring, working and investing in Belize -- a best-seller on Amazon.com)
San Pedro Cool (the first and only visitor guide to Ambergris Caye)
Belize First Guide to Mainland Belize
UpClose Central America
Belize Book of Lists