Don't Microwave Honey
By and large honey will stay liquid only if it has been processed. By processed, I mean heated until all the goodness is gone. That stuff you buy in the supermarket that stays liquid forever has had pretty much any of the good qualities natural to honey boiled out of it. The only honey types that will not crystallize in time are: tupelo, acacia, sage or black locust honey.
The crystallization that occurs is natural and inevitable. Once crystallized, honey will still have all of its benefits. Again, the heat is what destroys the enzymes that are in honey and also adversely affect the anti bacterial properties of honey. Those characteristics are what make honey good for you. Too much heat ruins that.
You don't want to heat honey above 104-105 degrees Fahrenheit. Microwave heat is way north of that. If you don't care and just want honey for the sugar, no problem. But if you want to continue to have the health benefits, please heat your honey slowly and below the temperatures mentioned.
Good luck!