I'll take...
Myself as an adamant and vocal Christian rather than an adamant, vocal anti-theist.
(And I do mean Christian, not Jew...if I'm switching, may as well switch all the way, after all, part of how I came to atheism was via atheistic/agnostic Jews and the fact that I simply cannot reconcile the idea of a just God with the Holocaust, and as I've said before, as there ARE Jewish Atheists, I don't think Jewishness is irreconcilable with atheism or agnosticism--again, Jewishness, yes, Judaism, no, as that's the religion by itself--whereas "Christian Atheist" IS more a contradiction in terms, it seems, you can't be both...and anyway, I couldn't picture myself getting fired up about defending and promoting Judaism the way Evangelical Christians do...radical Orthodox Judaism aside, Judaism seems the most "mellow" of the three Abrahamic religions, at least in its current form and if you're not Orthodox...maybe it comes from not having a state until recently and not having a messiah yet come to rival another religion's messiah, but I digress.)
What would I be doing?
Probably still majoring in English...but double-majoring in Religious Studies as well, as opposed to minoring in Political Science...and I'd probably go to Church, I suppose...and read a lot more religious authors and a lot less atheistic authors...CERTAINLY I'd be no fan of Nietzsche, Hume, or Hitchens, or many atheistic authors...I probably wouldn't want to be a writer, but a speaker, probably a big-time preacher, which would really take a load off my mind about how I'm ever going to make a living, it'd be so much easier if I could just preach, I'm a good public speaker and love to do it, and of course I already internalize and quote books--though now it'd be Scripture and not Shakespeare, lol--so I'd be the kind of people that Hitchens always debated against and that you see on TBN and such (anyone else watch that? I'll always turn to those religious stations late at night if absolutely nothing else is on or I'm killing time before I start a DVD, it just fascinates me how these people say what they say with such conviction...I don't agree at all, and often I'm taken aback by just what they DO get away with saying, but still, since I never DID go to Temple when I was religiously-Jewish, and obviously never Church, it's interesting to see what that's like for people...I'd never go myself, I know myself too well, I'd want to argue the whole time with the pastor or preacher and anything I'd say would offend him and his group and they'd likely offend me...and I'm find debating in the public sphere, but I don't want to intrude on people's private space and time and spoil there private enjoyment there, after all, I wouldn't like it if someone burst into an English class of mine to say why all literature is stupid or why they think D.H. Lawrence is the work of the Devil or anything...)
What would I be like, I think?
I think I'd probably be a lot more kind-hearted and empathetic in some ways and a lot less tolerant in others, and less analytical as well as less rude, or caring if I was blunt or rude with strangers, as I'd fear Divine retribution, I suppose...
I think I'd be a lot less conceited and arrogant but far more full of myself, if that makes sense...I'd probably be humbled or scared or awed into thinking less of myself and of the contributions of human beings, and so probably not take as many chances and be as brazen and self-sure as I often am, but if I always thought God and Jesus were on my side and I was not only right but defending something Divine and holy...I'd probably end up viewing myself as righteous by extension and always in the right, and be more insistent and rather than arrogant, and I don't think I'd like people who disagreed with me much, whereas I love people that disagree with me here. I'd also probably be more of a joiner and a group person, I think, if 'd grown up going to Church with Bible Study and all, whereas I'm not at all a joiner and an odd mix of extroversion and anti-sociality now...I'll talk to anyone, but I like to find the most secluded place I can for breaks during class and I stay by myself as much as possible, and I don't count many as real friends, and I dislike most groups intensely, or even the idea of groups and the people in them.
(So Putin, we'd still be the best of buddies!)
None of my friends that are atheists would be my friends...we'd just never have met, half of them I met while they or I were having a debate on theism/atheism, or met and we bonded over that, or it gave us the chance to meet, and so on...
And those are most of the good friends I have right now, I have friends that ARE strongly theist--for some perverse reason, my Jewish Atheist self seems to run into a lot of Catholic friends for a double dose of irony--and I suppose I'd probably make a larger circle of friends for myself, but not give them all as much care and attention as I do the few good friends I have now, I guess I'd be spread thinner and amongst more people that way.
Aaaaaand I hate just about ALL of those characteristics to some degree or another, hence the reason why I'm not like that...? LOL
^Yes. That was long. If I were Christian-me...
It wouldn't be any shorter--some things are just constant. ;)