"So then he (God) has mercy upon whomever he wills, and he hardens the heart of whomever he wills(Romans 9:18)."
"Your lives will be incomplete unless you reverently study the teachings of Jesus."
-Ghandi
"If Christianity is true, why do so many unbelievers exist?"
If Christianity is false, then why do so many believers exist?
"How is one to be sure of which religion is correct? The odds in Russian roulette greatly favor not dying in any one turn, but play it daily and life will be short. With different religions saying what God does or doesnt permit, the odds of achieving Nirvana are kinda stinko!"
God gives the truth to us, if we listen. While it is true that we cannot `prove' any religion to be correct, it is also true that you cannot prove yours correct. You are not immune to having religious beliefs. The afterlife is like Russian roulette, you say? That implies that you can walk away from the table! Do you realize the absurdity of the idea? Death comes to us all! We play that Russian roulette game daily, whether we like to or not! You don't know for a fact that when you walk out the door tomorrow morning, it won't be the last time you'll do that. We can't avoid death. That revolver is going to be pointed at your head, whether you want it there or not. So you'd better have some religious belief, just to be on the safe side! Your odds of going to heaven (or `Nirvana' as you say) will be drastically reduced if you refuse to take any stance.
"How are we supposed to have a chance when He lets 200+ religions mislead us?"
We have a plentious chance. You're making the assumption that the other 200+ religions have the power to mislead in order to `prove' your point. Actually, they aren't as convincing as you say. The homely truth is unpalatable. During the time of Moses, people didn't like what Moses said, so they created their own religions. But "an idol[i.e., any god besides Yahweh] has no real existence(1 Corinthians 8:4)." I believe other religions were made by either human beings with no divine inspiration, or by the inspiration of demons. A lot of people become unbelievers because they hear so much of God's word that they get itchy ears and wander away from the truth. It's not that the religions are particularly convincing. It's lousy odds to think that no religion is correct when there are 200+ religions out there, too. There's a chance that your position, "no religions are correct" isn't true. Certainly, I see the position as part of the 200+, because it's a worldview, a subjective perspective on reality, and it may or may not be the right one. You just picked a different number on the roulette wheel. But then again, I believe that all people once knew the one true God, but got "dissatisfied" with Him, and so replaced him with other gods. I believe that even though historical evidence doesn't point to this, God predates history, and people began with an orally based religion, one where there was only one true God. And all people on earth began with that faith. Christianity is unique because it's the only religion that has a person who has paid for and pardoned us of all our sins, all the evil things we have and will have done in our entire lifetime, it has a person who reconciles us with God forever, a person who makes us into new, holy creatures, through no merit of our own. Jesus.
"I don't understand how you can be a believer when there are hundreds of other religions in the world that contradict what you believe."
Is the truth negated by the presence of lies? Did the presence of the geocentric universe negate the fact that the earth revolves around the sun? The fact there are hundreds of other religions out there is irrelevant to the validity of a religion.
"How are we supposed to know which religion is right when there are so many different ones?"
God inspires us to find the bible to be the right one. The bible is more compelling than other religious texts. The Hindu Vedas are indecisive and purposefully vague. Their message is basically, "I don't know," simultaneously being atheistic and religious at the same time, denying the existence of gods, then saying "maybe they exist" or vice versa. It makes very little sense. The book of Mormon has no archeological evidence even remotely hinting at what it says. There were no biblical wars in Missouri, no Jehricho in America. Islam denies that Jesus died, even though historical accounts and even atheists support the crucifixion of Jesus as being a true event. The bible is also unavoidable. You can't turn on the radio or TV in any country without being exposed to at least a little of it. Intuitively we know that the bible is the correct religious text. It's the most compelling religion, and by far better than being totally unprepared for the afterlife.
"If God is so powerful, why does He let cults form and gather followers?"
Does God stop cults from starting? No. And people do get suckered in. But that's only a small percentage of the people attending their lectures, or whatever. And the dedicated members are few, and the attendance rates decrease over time. I believe God puts people in the would be `sucker's' life to stop them from falling in to the trap. My grandmother had a talk with me about the UBF organization I used to belong to. I talked with my parents about it, too. They convinced me to leave the group. They believed themselves to be the "true church," isolating themselves from what I consider the "true church," the body of Christ. They called the other denominations "lazy." That stuff made me leave. Attendance wasn't great at the group, either. There was a significan't dropout rate. To complicate the issue more, one's previous religious beliefs also factor in the individual response to a cult. A Christian would not become a Hare Krishna unless dissatisfied with Christianity. So I believe God has already intervened in this regard against cults. At least, new ones.
"(God) apparently isn't making any personal effort to guarantee that everyone hears the word - though He seems to have made plenty of Hell - space - time for them."
Christianity is everywhere. There are very few countries who don't at least use `Jesus' as a swear word, if nothing more. They're aware of the existence of Jesus, in some form or another. Places like China have house churches. They're not on every block, or even permitted by the government, but they're relatively abundant. Interpret this stuff however you want, but I see it as an indication that Christianity is a religon that everybody at least knows a little something about. "Their(speakers of God's word) voice has gone out to all the earth, and their words to the ends of the world(Romans 10:18)."
"I have been found by those who did not seek me; I have shown myself to those who did not ask for me(Romans 10:20)."
There's always some denomination somewhere that's handing out tracts and bibles and preaching and evangelizing or wearing religious t-shirts or something. I don't think hearing the word is the problem. God's word is hard to avoid. It seems like a greater concern is getting people to accept and believe it. People are having longer lives, and God's word is translated in thousands of languages, disseminated on the internet, there's plenty of Christian missionaries and missionary movements...it's going places. I think that's plenty of effort.