Could anyone help me explain things? :/
I've been in the fandom for a while now....quite a few years.
My parents are split, and I used to live with my mom and stepdad. (Now i live with my grandparents, because things happened and they moved to another state and whatever....anyway...) My mom and the rest of my family are very acceptiong, non-judgemental people. When i told them about the fandom, and that I wanted a fursuit and to go to cons, they all accepted it. They asked the questions they wanted to, and i answered them as best I could. (my grandma went online for more information, and found something about yiff....she asked me about it, and I explained to her that its not weird, compared to some fetishes, not all furries like yiff, and I dont like it either. which is true!)
I went to anthrocon and furfright last year, and had a blast.
however, my dad, no matter how many times I explain things and show him things (like pictures from the cons), he still thinks its something that "isnt right" he is constatly questioning me about why I like fursuiting...and what is so interesting about meeting up with other costumers.
He used to play Smokey the Bear at local fairs, since he used to be on the fire department, so he understands that sometimes being a character is fun, but he doesnt understand why I sometimes chooose to go on fursuit outings, and take so much care of my suit, and why i love going to cons SO MUCH.
He may have watched CSI, but im not positive on that. I've even explained yiff to him, like i did to my grandma....he always tells me that he doesnt mind, and that i'll like whatever i choose to like...he accepts everything else I do much more than he accepts my love of the fandom, and I dont know why. I cant seem to make him believe that the fandom is a ton of fun for me, and its a community that i have fun in, and have a lot of friends in(for once). He loves my artwork though, even though its all furry-related. Its like he doesnt make the connection that a lot of the things I love about the fandom is ART RELATED, and that the fandom is what inspires me, and has helped me improve over these years.
can anyone help me explain to him that being a furry isnt a BAD THING? I dont want him to just change his thoughts in a second and suddenly decide that "oh yeah, verythings fine, i dont know WHAT i was thinking!" I just want him to realize that this is an important part of my life, and that nothing that i do in the fandom is BAD, and for him to stop constantly questioning me why i like it so much.
as a side note, he also doesnt understand my love of my little pony:friendship is magic...he says its too immature for me...but that i can understand. its hard to explain the internet, not to mention BRONIES. i dont expect him to understand everything on the internet 110%.
"And above all, don't talk about furry as if it were something that defines you. It's not who you are, it's just a set of activities you enjoy, and you like sharing them with your friends."
I'm glad to see more people out there who think this way. Too many riteous furnatics.
But he doesnt understand why I sometimes chooose to go on fursuit outings, and take so much care of my suit, and why i love going to cons SO MUCH. [...] I dont expect him to understand everything on the internet 110%.
And here's the thing: He might never understand it, he might never get it, he might never be completely cool with it. That is okay. If he lets you go to conventions, draw your art, talk to your friends.. this is not a problem.
I understand the desire to have your father be totally down with your interests; I know my parents don't appreciate or enjoy all of my interests, and vice versa. You at some point just have to say "Dad, I know you just don't quite get what I'm into.. and that's okay. You'll have to trust this is something I just plain like." Him asking questions and being concerned is.. really just beign a concerned parent. I do understand the furstration of your Mom and stepdad being much more relaxed about it; you can always have him talk with your Mom.
Just relax, though. he doesn;t -have- to think the Furry fandom is great. You're the one doing that. 
If parents don't understand Internet culture, much tragedy can result from it. Explain it to them a little.
Why do you suit? If I had one, I'd do it to put smiles on people's faces Perhaps that explanation would help your father understand a little better?
Make them see videos of a convention like AC so they can't believe anynthing that is made.
Maybe a good way to explain it...is to relate it to something not furry. Does your dad like football, or cars, or something else that you aren't into? Perhaps explaining that you enjoy costuming as much as he enjoys one of his pasttimes...may help him understand. It's never about being confrontational, it's more about just explaining that there are some things one person likes that another may not care for. It doesn't make it bad...it just makes it different.
I second KP's suggestion of comparing it to something your Dad likes to go and do. People enjoy what they enjoy, and sometimes pointing out to them that your enjoyment of something is similiar in intensity, in what you get out of it emotionally or intellectually (even if the subjects are completely different) it can help them see how important it is to you, and that you're getting a positive benefit from it. You mentioned improving your art through your contacts with other furs; can you think of any other areas of your life, or your outlook on life, that are better because of your contact with the fandom? "I'm a better person because of life-lesson x and I learned that from Uncle Kage!" (for example ^_^)
On the particular subject of MLP, approaching that from the direction of Shrek might be useful. That movie is great for kids because they don't get the slightly more mature or dated references and still have a good movie. It's also good for adults because we do get the more mature/dated references and still have a good movie.
can anyone help me explain to him that being a furry isnt a BAD THING? I dont want him to just change his thoughts in a second and suddenly decide that "oh yeah, verythings fine, i dont know WHAT i was thinking!" I just want him to realize that this is an important part of my life, and that nothing that i do in the fandom is BAD, and for him to stop constantly questioning me why i like it so much.
An old story but I'll tell it again:
Years ago, a co-worker of mine who had seen the ER episode and knew I went to Furry cons (I'm pretty open and honest about going to them---I've got nothing to hide) with a "knowing" grin on his face asked me what they were like. So I handed him a copy of the conbook (not that I carry one around with me at all times in the unlikely event someone's going to ask me about Furry stuff, but because it's actually relevant to my career and I had been sharing a bit of editorial humor with another co-worker).
He flipped through it, looking at the artwork and stories, and you could just see the light go on.
"Oh... so this is about cartooning and animation, right?" he said after a few moments.
I told him there were costumes and stuff too, but yeah, that was pretty much it. Along with a gentle admonishment not to believe everything he saw on TV.
Not sure if it'll help in your situation, but I've always found the easiest way to convince people Furry isn't a bad thing is if you don't act like it's a bad thing. Focus on what we are, not on what we aren't. HTH.
It looks like you have already told him about the things you do. It's hard to explain to someone why you find something fun if the other person doesn't, but you could try asking him about the things he enjoys doing, and the things he did when he was your age. He probably had hobbies of his own, and enjoyed being with friends who shared his interests. It's the same for you, only with a different kind of interest.
And above all, don't talk about furry as if it were something that defines you. It's not who you are, it's just a set of activities you enjoy, and you like sharing them with your friends.