
(The remark in bold is a comment by an atheist friend of mine, and my response follows.)
"I'm glad that Christianity has made you happy. However, your statements about how people of other religions are innately unhappy while Christians are innately happy, fulfilled, and helpful to others is a dangerous generalization and stereotype that reflects your biases, not reality."
That isn't exactly what I'm saying. I never said anything about being happy. I did mention joy. Joy in the Biblical sense is more synonymous with peace and hope than pure happiness. Obviously it goes beyond those and is not entirely separated from happiness - else we wouldn't need a different word - but it doesn't just mean being happy. I can be - and often am - unhappy with my life at times, due to stress or pain or what-have-you, yet I still feel joyful. I can still praise God, for the work He is doing on me in my present tribulation and for the promised outcome once it is over. There is joy in resting in the knowledge that nothing can separate us from the love and care of God, and that all things - even the evils of this world - can work together for good to those who love God and follow in His purpose for their lives.
As to the other, once again I fear you missed my point. There is nothing about a Christian that makes him/her innately more happy, fulfilled, or helpful than somebody else. It is true that being a Christian and truly seeking God's will should produce the fruits of the Spirit (love, joy, peace, patience, kindness, goodness, faithfulness, gentleness and self-control) as a "by-product" if you will of having Christ working in you. But the rest can likely be attributed more to personality, and it is of course silly to think that Christianity has a unique difference in inborn personality of its members. I know many decent, loving individuals who follow Islam, Hinduism, and Judaism (I only know one Buddhist), and I would call them generally happy and helpful, and at times fulfilled. I would say this about many Christians, too.
What I said was that I know people of other religions who still struggle with sin and suffering despite going through their religious instructions. When I compare Christianity with anything, I think not only of the abstract knowledge of both I have, but also specific individuals that embody the religion. I follow this general rule: "But when we are comparing Christians in general with non-Christians in general, we are usually not thinking about real people whom we know at all, but only about two vague ideas which we have got from novels and newspapers. If you want to compare the bad Christian and the good Atheist, you must think about two real specimens whom you have actually met. Unless we come down to brass tacks in that way, we shall only be wasting time." - C S Lewis, Mere Christianity
Christianity is unique in one important area: it has the concept of grace. You won't find that in abundance anywhere else. (Please note the following descriptions do not contain a full account for brevity's sake.)
Take Buddhism. According to Buddhism, evil is in the world because of human desire (see The Four Noble Truths). A Buddhist is on the path to nirvana, i.e. the "puffing out" or "extinguishing" of desire. "Sin" in Buddhism has to do with violence and greed. If you sin in Buddhism, you contribute to the evil, and there is no teaching of forgiveness or grace for personal cleansing; you must pick-up, continue on, and should you ever achieve nirvana you will no longer care (or rather, it will no longer affect you).
Take Hinduism. Karma is the primary effect of goodness and sin. If you do good things, karma will reward you in this life or the next reincarnation. If you do bad things, you are stuck with them as well and will be punished. The goal of Hinduism in many ways is to do more good than bad so karma stacks in your favor.
Take Islam. Islam is very much about earning your way into heaven. You do what is right, right being defined as obedience to the teachings of their Prophet, and the closer you can control your actions to match up with the laws, as well as the more you contribute to the spreading of Islam, the better your place in heaven. Punishment is strongly enforced in Islam as well for those who fail to live up to the standards.
Take Judaism. Judaism begins to attain the idea of forgiveness. Jews must follow a strict code of conduct for purity and uncleanness, and sinners must make sacrifice to God to have their sins "pushed back" or "overlooked" for a time. Sin is punished heavily, but repentance and sacrifice will earn one's place back into the favor of God.
Now take Christianity. There is a code of expected conduct, which serves the purpose of showing that nobody can live up to it on their own - except Jesus, who died in sinners' place so they could be free from sin's bondage. The goal of Christianity is to have a relationship with God, not follow a to-do list of morals, and sins are forgiven in faith. Grace is God loving you when you are an unlovable, selfish being, and forgiving your sins even though you do not deserve it. This is the one I know of personally, and I can tell you that the experience of forgiveness is amazing and humbling and life-changing. But even outside of my own experience, I can intellectually discern the differences in the religions. I may be biased in which one I choose still, due to my upbringing and position on the globe, but the religions can be objectively divided as to their differences, and if any of them are true, only one of them can be (their core beliefs are not interchangeable).






