Can I prevent honey from congealing/hardening in the pantry?

Keep it stored in an airtight container, so that it doesn't absorb moisture from the air.

If it congeals, put the container in hot water until honey is liquid (~10-15 minutes).

Hmm, sounds like you're getting "raw" unprocessed honey, which is a good thing, because that kind is in all ways better than store processed, but it tends to crystallize very rapidly.

To return it to it's liquid state, heat it slowly in a double boiler to around 145(f). It should turn clear and liquidy. Once it looks nice, cool it off by adding some cold water to the pot. Don't heat it in a closed containter: honey increases in volume when heated.

If your honey is in a glass jar, you can also just remove the lid and put it in the microwave for 20 - 30 seconds or so. All you're trying to do is heat it up so it goes back to liquid form. (But don't microwave it in plastic! Yuck!) I've never found a way to keep raw honey from crystallizing in the first place, though.

The answer to the question is: store in the freezer. Honey will not crystallize under 65 degrees.

If it does crystallize: keep your honey raw and maintain the antimicrobial and antibacterial properties, don't warm above 105 degrees. Never microwave it. Raw honey has never been heated above 105, usually warmed by a light bulb to help it flow when extracting it.

Be gentle with your raw honey.

I learned this from my beekeeping mentor. I have two bee hives.

My family owns a bee company and we have found the best way to melt honey back to its liquid form is to immerse the whole bottle with lid still on in a crock pot filled with water and turn it on high for about an hour or so, depending on how much honey you're reheating. Fill the crock pot so that the water hits below the lid though, because water will ruin your honey. And just keep checking your honey every 30 minutes or so.

there is nothing wrong with your honey, honey that behaves that way is showing it's higher quality. You can use it as is, it will melt when you cook with it. It makes an excellent spread as is (such as on toast), and yes it will last that way for decades and even centuries if it's sealed properly.

If you really must reqliquify it, then just place the jar in some warm water and wait a while.

According to this answer, honey should be stored at 70-80 degrees Farenheit (described as room temperature, though that's warmer than many rooms I've been in). I used to store my tea honey in a cabinet that's on an outside wall, and I've seen less crystalization since moving it to a cabinet on an inside wall. That said, I still get some crystalization, especially in winter when the kitchen temperature ranges from 60 to 70. I haven't yet succeeded in preventing crystalization entirely, even though I keep it in tightly-sealed glass jars.

Other answers have addressed how to rescue crystalized honey.

From this question it seems that you might be able to store it with the comb to make it last longer before crystallising.

According to this site you can store the comb for more than a few weeks by putting it in the freezer, it will thaw out as runny honey apparently.

Get acacia honey - it practically never crystallizes.

I microwave the honey in 30 second increments until it melts back to a usable state. It works fine and doesn't recrystallize for a couple of weeks. Then I microwave again.

I love maple syrup when its in the pure forn(meaning it has not been diluted with the bought syrup) and found keeping pure maple syrup in the freezer was my answer. It will not freeze. Pours kinda slow tho. I say that to say this,maybe honey will react the same way.

Easy way to prevent crystallization: store honey in a clay jar!! ( ceramic). Never crystallizes.