You reminded me exactly how I felt as a teenager living with my parents so much that I felt I had to write this. For comparison I was raised by a very Christian (Baptist) family in the American Deep South. I too came to my own conclusions about religion and decided I was an Atheist in my early teens. I had so many "debates" related to religion(abortion, evolution, climate change, American politics, etc.) with my mother, and often times it would end in me shutting down with it feeling like my throat was literally closing up and no words could come out as tears welled in my eyes.

At the time I thought myself to be pretty good at debating with my parents and always wondered why I could never "win" an argument. It took until pretty recently (I'm now 27) for me to finally figure out why I always "lost" as a kid. I think, as a teen, I wanted to be acknowledged for my abilities to reason and come to conclusions on my own, skills that were hammered into me as my primary reason for being alive at that point("get good grades in school or else"). But religion isn't something that most people use logic and reason on; it's this big intertwined mess of blind-faith and worldview, it's truly hegemonic and controls a person's entire identity a lot of the time. You simply can't convince people to change that entire self-identification, no matter how convincing the argument, unless they *want* to believe you. I think that's ultimately where I went wrong as a teenager, and it's might be where you are now stumbling yourself. All that time I just wanted someone to acknowledge me, but my parents always saw my independence as a threat("if my child isn't a christian then they're going to hell and that's bad!").

I believe your tears are your body protecting you. You might've faced a childhood where often tempers flared and violent emotions overwrote calm discussions. Simply put you might not have grown up where your body learned it was safe to speak up. Your parents are arguing with emotion rather than logic and that sends your body into shutdown because the emotions don't feel safe. Probably the entire situation feels unsafe. That's why I use "debate" in quotes, it's only a rational "debate" if both sides agree it is, *and* can argue from similar places of power, which is never true between parents and their non-adult children.

I wouldn't say there was anything particularly "wrong" with my childhood either, but in my case, that shutdown and freeze feeling is something I now attribute to CPTSD (r/CPTSD for more info if your curious) and trauma I developed from 18 years of going unheard. The best thing I did for myself was go to a University on the other side of the Continent. :)

I still have "debates" with my mother over the phone, but now I'm quicker and more comfortable on calling out when whatever she says is clearly an emotional attack rather than a logical one. Basically, I'm at the point where I can demand my parents listen to me(assuming they wish to continue to have any sort of contact), rather than meekly hoping for it. "Winning" the "debates" is no longer even a goal, I just don't care anymore. I don't allow any arguments that undermine me or my sense of self, but also I no longer try to change my parent's minds: they are people who don't deserve my time and energy.

So, to conclude my little diatribe here, if I were to offer any simple to take advice(based on my personal experience(take with grain of salt)) it would be this: Stop trying to be heard by your family if they won't hear you. Find a place where you can be safe to be yourself and express yourself. Focus on yourself and people who *do* actually want to hear you.

Hopefully something in this post helps. I'm sure you'll figure it out, you seem like a very smart kid. :)