I am a 15 year old atheist: help!

[Thor]

I was raised Roman Catholic since birth and have believed in the teachings of the bible because I have been told it is the only way. My parents are always trying to push their Christian ideals on me and it bothers me a lot.

Of course your parents are pushing their religion on you. That's how religions work. They have to get their claws on you when you're young and haven't yet developed the ability to think critically. After all, what adult, not previously indoctrinated in this nonsense, is going to believe tales of a man who was born of a virgin, walked on water, healed the sick with a touch of his hand and rose up from the dead?

I try to have discussions with my father and debate with him but whenever I throw something at him(not literally) it's like it doesn't count.

Your father is convinced his position is right. I really doubt that anything you say will change his mind.

What do I do to get past the wall of irrational thought and convince them once and for all?

You stated your problem quite clearly when you mention "irrational thought". It is very difficult to argue rationally when your opponent thinks irrationally. You can point out things that don't make sense and they will respond with crap like "We can't know why God does the things he does", or "God has his reasons", or "Somehow, God did it", or "We can't judge God", or my personal favorite, "I just KNOW it!" (Yeah, they just KNOW things that are impossible to actually know.)

Are there any arguments I could use?

One of my favorites is to ask if "God" loves us. They will no doubt respond "Of course!". You then ask them if "God" created everything (They'll no doubt say yes). You then point out that if "God" created everything, that means he created bubonic plague, smallpox, polio, rabies, malaria, tetanus, botulism, poisonous mushrooms, etc, etc... You then ask how it is that a "loving" God would create things that harm and kill us. This is completely inconsistent and contradictory. But be prepared for one of the insipid answers I mentioned above. They may also throw out something like, "Those things are the work of Satan!" Of course, this opens up a can of worms for them because you can then ask how it is that "Satan" is more powerful than "God".

Good luck!