my favorite, drawn fron aquinas and kant, has to do with the fact that we have a sense of right and wrong, of goodness and badness. this is not based on that which is easiest or that which produces specific results, but for some other reason. if there is no god, what would it be? (there are arguments to refute this, but they do not hold up.)
there is also, again from aquinas (and following through thomas jefferson and indeed clarence thomas), the notion of "natural law," as in "we hold these truths to be self-evident." the idea that there are metaphysical laws that are as inviolate as the physical laws of the universe demands a higher order of organization -- strong evidence that all this didn't just happen.
a little more difficult to argue for, and the locus of most religious dispute, is the relatively minor points of just what god's up to. to the extent that we might learn what active role god takes, we encounter a whole lot of background noise, extending from the tinfoil-mitred revelation-thumpers to the latter-day seers of many sorts. but there is something of which we can be certain, and that is that prayer does work. i have seen it time and again, as would your friend were she to watch for awhile. this isn't to say that god is some kind of cosmic santa claus delibering everything for which we ask -- bill buckley famously wrote that "certainly god answers all prayers, but sometimes the answer is no," which is i think accurate but a little stark. i much prefer the formulation that alan keyes uses, "sometimes god does the right thing in his way rather than my way."
while i do not take the stock that many do in the bible (there has been way too much opportunity for it to have been corrupted over the millenia), there is one thing in it that i think cannot be doubted: "seek, and ye shall find." if your friend genuinely seeks god, she will not be disappointed.
dep
This is almost what I tell her ( and what I believe) ...that God is the goodness in people and to look around at this earth and see how everything fits.....all its resources..water, air, sun, oil, food, rain, the brain, our complicated body and how it works, all our feelings, babies.........some of these things that I just can't see how they could have evolved. But, evolution has fossils. Proof.