I talk all the time about my faith with people I hang with, in lab, in class, with my science nerd buddies and with my artsy friends... and my conversations are always without fail very positive on both sides... I find that conversations about faith can be very enjoyable and positive if you keep to a few things.
1. Never come off as prostleytizing or give the impression that you think you know more than or are more right than anyone else. People don't appreciate preaching, prostletyizing, arguing, or being lectured at, and seeming so will only get in the way of your message. If you come off as any of these 4 things then people will assume you are cocky (you seem to assume you know more than/are smarter than them), unyielding, stubborn, narrow minded... etc. So just keep an 'open' posture - I like to share from my experiences ("this is how my faith touched me, ... that's just me... but I feel like it's really made a big difference in my life..." from the point of view of "it's just something I care about, and that's why I'm talking with you, because we're friends and friends talk about random topics of personal interest". That way there's no defensiveness or weird awkwardness, you're just getting to know the other person)
2. Show, don't tell. This is key. Everyone has read that Jesus did this, or Moses did that, or buddha is... and everyone comes into a faith conversation with their own preconceived opinions of what YOU believe when in fact usually they have no idea what YOU believe or why faith is personal to YOU. If you can show through YOUR experience why god means something to YOU then the focus is not on the person's XYZ assumptions about your belief, but about the specific story of how god moved YOU. For example I'm a Christian but grew up atheist. So when I'm talking with an atheist, I kind of have an idea of the arguments/ prejudices they might have (of course it's different for everyone), and if I started blabbing on about how the Bible says this and says that, it starts sounding preachy, boring, and non-exciting, and they start reading into what I say everything they think negative about Christianity, etc. But if I start talking about my EXPERIENCES with the emphasis on SHOWING not telling how faith has changed my life, then it's like, oh, whoa, she really has a story to tell, maybe she's not crazy, maybe this thing (as weird as it seems) really did do something to her ... and you should emphasize that perspective in your essays.
It should be from the perspective of "let me tell you a story about this thing (it just happens to be religion) that affected me..." not "let me tell you a story about how religion is awesome and changed me."
We live in a postmodern pluralistic society, and I think our culture (at least our generation) values A) openness B) acceptance C) experiences. People in general (my friends at least) don't want long complicated arguments about proof, people care about experiences, valuing the human being and the person. That's why celebrities have blogs and twitters and facebook pages - the common person wants to know about the PERSON behind the facade. It's the same with faith - people in general won't care whether youre a liberal or conservative or green or yellow they want to know YOU. If you're nice (loving, accepting), they will be open to hearing your message. As long as you keep the openness and acceptance I think that things will be ok, just don't speak to people's defneses. To be convincing in today's society, we must be personal, not merely pragmatic or dogmatic. And it's the same in your essay. Be personal, not dogmatic. Be relatable to a non-believing audience.
Let me illustrate from an example.. let's take abortion (since this is so commonly a debate conflating many opinions with different values). Ironically, both sides to the abortion debate share one thing in common: they value the individual, and they value well-being and health. The pro-abortion people think that abortion is better for life/well-being/health, and the anti-abortion people think abortion worse for life/well-being/health. Any conversation involving opposing views and opinions often revolves around a common interest. (as a disclaimer I'm not trying to bring up a debate on abortion, just using an illustration of how opposing sides often have a common goal, so please don't bring this up in further discussion).
Now when I talk about faith with a non-believer, we both have many commonalities. We value acceptance, personal experiences, etc. With your essays, there are a few things the scientific culture values and you should relate to as well. I.e. objectivity, analysis, and knowledge. Show in your essay how you used objectivity, analysis, and knowledge to come to decisions about something as complex and nuanced as your faith. Be perspicacious, analytical, critical.
The tone of your essay shouldn't come off as, "so like, I've always liked FAITH and faith this and faith that and church blah blah... science was against it, blahblah, I was stressed, but I'm back at faith again." Thats dumb. Your essay should more be along the lines of, "I've always been a critical and analytical person, (with an emphasis on this), and increased examination and deep thinking caused me to come to some essential questions about fundamental issues that were deep to me and my cultural traditions. [address the questions and how you resolved them]" mostly you have to convince your reader that you are just as analytical, and even more so, after this critical thinking about your faith, and that your knowledge has led you here. If you come off as naive or ignorant, it's not going to fly. But if you can (going back to the above) show, not tell how your personal experiences have led you to be analytical, sensitive, and deeply critical, then I think you'll be fine.
In the bigger picture, it's about relating to another culture's values, and perspectives, and showing how you are relevant to and agree with many of their values and opinions. Think New York Times - they talk about lots of controversial issues from a liberal standpoint, its not necessarily bad to talk about controversial topics, as long as you do it right... our culture isn't anti-controversy, it's anti-preaching, anti-ignorance, anti-closedmindedness.
If you want any personal feedback, feel free to PM me =]