One of the things I love about Christianity (and why I believe it) is not just that it is philosophically possible, but that it is theologically possible. By philosophically, I mean that we can make sense of it; but we can do this about a lot of religions.
Though I am not a Muslim, I can understand and learn Islam. I can see how it addresses that the world we live in is not quite “right.” I can learn how Islam deals with human nature, what to do about our own imperfection, how to please god, etc.
This is what all religions do to varying degrees. Though I may not agree with the “philosophies” of a particular religion (how a religion deals with the problem of evil, how people are “saved,” how it deals with sin, etc.), I can accept that they in some way make sense. Though I don’t believe in karma, I can understand the philosophy behind it. While I disagree with the philosophies behind many religions, that does not make the philosophies themselves wrong.
But when it comes to the theology of a religion, that is the study of the nature of God (or gods, supernatural force, etc.), this is where I would argue all other religions fall short.
One of the biggest areas that separates Christian theology from all other religions is the atonement. When a Christian speaks of the atonement, they are speaking of what Jesus did on the cross. He took the penalty of our sins and the punishment we all deserve; he made us right before God. The atonement reconciles us before a perfect God.
What is unique about this is that there really is no other religion that fully atones the wrongdoing of those who make it to that religions respective “heaven” (or enlightenment, etc.). There are things that people must do for a chance to make it to heaven, but for the people who are good enough to get in, nothing is really done with their sin.
For example, in Islam you have the five pillars of Islam, or in Buddhism you have the eight-fold path. These are things that adherents in these religions must do make it to heaven. And if they do these things and the other particulars of the religion and make it to heaven, there is a huge problem, what happens with the wrongs they committed? Even if their good outweighs their bad, the fact remains that they still need to be held accountable for the bad they did.
If God is perfect and just, then he must do something with sin. He cannot simply excuse it as if it did not happen as that would make him terribly unjust and even unloving. This means that we have a huge theology problem if God simply dismisses all the evil that we do. A God that does not condemn evil certainly is not an all-loving God.
And this is where Christianity theologically makes since. If you trust in Christ and follow Him with you life, you are “saved.”
If you confess with your mouth that Jesus is Lord and believe in your heart that God raised him from the dead, you will be saved. For with the heart one believes and is justified, and with the mouth one confesses and is saved. -Romans 10:9-10
Salvation is not earned in Christianity, it is given by God’s grace. But in the Christian religion, when you go to heaven, it is not as if God simply forgets about or does not deal with your sin.
Only in Christianity do you have a God that actually deals with the sins of the people who go to heaven. He did so through Christ. Jesus lived the perfect life we could not live, and took the sins of the world when he died for them on the cross. Jesus atoned for our sins which is what makes us right before God. Only because Jesus bore our sins on the cross can we stand before a perfect, holy, and just God without condemnation.
It does not make theological sense for God not to deal with the sins of the people who go to heaven. This is also why it does not make sense for us to think that by somehow doing more good than bad that we should go to heaven. Even if your good outweighed your bad, the fact remains that you still have done “bad” that needs to be accounted for.
One final note. I am aware that many Asian religions believe in some form of karma and reincarnation where in each life you have the ability to progress more and more towards enlightenment (or nirvana, etc.). The thought is that as we live purer and purer lives, you can get to the point where you make it to or are ready for some sort of enlightenment.
The problem is that no one is perfect. Even the holiest of people still have faults. So if some guru in India only commits one sin in his entire life (which is simply impossible) that still makes him imperfect and that one sin needs to be atoned for.
In Christianity you have a theology that gives you a perfect, loving, and righteous God. I’m not saying that this proves Christianity is true (though I believe it is), but I am saying that at least in Christianity you have theologically possible God. And this is a great truth indeed.