Q&A for How to Become a Curmudgeon

Sure. The "rules" of Christianity don't regulate what kind of personality you must have, you are free to be a curmudgeon if you like.

There is no single answer to this question. People can be ill-tempered for any number of reasons, but a primary cause is environment, and an inability to effectively express yourself through communication. Being ill-tempered is often a by-product of frustration, and frustration often comes from not being able to understand or express something.

Someone who can smilingly accept another's opinion without taking that opinion as a personal attack.

No, a curmudgeon is not the same thing as a neck beard. A curmudgeon usually means a grumpy old man.