Christianity is true and all other religions are false because only Christianity provides:
1) a reasonable answer to how the universe and us got here. I know you all are familiar with the cosmological argument, so for time and space's sake I won't repeat.
What does 'reasonable' have to do with it. Atomic theory isn't reasonable, in the sense that you using. Nor is the theory of gravity. Rather, each is a conclusion reached via study, research, experimentation and other scientific undertakings. Reasonable isn't one of criteria. Reasonable isn't even very useful in life. A reasonable person would never get married, because no marriage will ever be as smooth as silk, so it will inevitably hurt. Yet people do it.
'Reasonable' is not a criteria worth considering.
Just to be clear, the end results of scientific endeavors are reasonable. But as a byproduct, not as the only reason to look for the answers. You're doing it wrong.
2) a reasonable answer to the problem of pain and suffering. Again, you all are familiar with that argument as well, so no need to repeat it.
More reasonable. Again, irrelevant. To expect everything in life to be nice and neat and 'reasonable' is to more or less guarantee that you're going to settle for lies, because, in this case, that is the only way to wend your way to 'reasonable'.
There are more obvious, more logical, more consistent, more rational, more easily explainable reasons for right and wrong existing in this world. All are grounded in reality rather than fantasy, so from your point of view, they aren't much fun. And they lack the pazzazz of 'sinning', which is the frosting on the cake for you guys. But we evolved being have no particular reason to be perfect. There has been no evolutionary pressure to be good all the time. So we're not. Don't go slathering your lack of thought all over the issue.
3) a way of salvation that does not rely on one's own effort to obtain it, thus one can not only receive the salvation but have assurance of it because it is not based on their own works. if you all are as smart as you claim to be, then you know what Hinduism, Islam, Buddhism, and others offer in the way of salvation and assurance of it, if anything.
Irrelevant. Religious salvation doesn't exist, and to believe that it does distorts your reality beyond measure. You're going through life using Play-Skol toys instead of knowledge and common sense. You are not dealing with reality, but rather a Barbie shaped view of reality that is just as distorted as the doll. Religion is a toy, that you keep trying to hit everyone else over the head with.
4) a God Who is the First Cause in the salvation process. God chooses to give salvation to someone and they are saved. This is related to 3 above. It is not someone seeking God and finding Him, it is God choosing to make the lost one found.
We're not lost, you just don't' see us playing in your daycare and, being spoiled brats and all, you want us to be there with you rather than out living an adult life. With no god, there is no path to your imagined salvation. Only you choose to want others to the useless religious tasks that you think are important, because again, no god is involved in the process. It is entirely human. And the religious tend to give 'human' a bad name by playing all of your games.
In addition, there is the personal experience that I and many others have had.
That is all anyone has ever had. Personal experiences. I don't know of any other kind for a person to have. That you have misinterpreted various events in your life as god-related is not very useful. Not useful at all, in fact.
Righteousness doesn't look good on anyone. Not at the level you are trying to reach. Please stop. You're embarrassing us humans.