For the sake of this argument, the premise is that the atheists are right. God does not exist, and all religions are mistaken about any type of higher power, intelligent design, etc. I want to examine for a moment the pragmatic effects of having Christians in the world.
I know that from time to time Christians do really dumb things. No one is perfect, regardless of religious affiliation. Christians and Buddhists, atheists and believers: we all have skeletons in our closets. So before I even begin, I’m going to give you the Crusades. The whole of Europe was deprived of education, even the ability to read and write. That would include the Bible. So you had thousands of very hot headed religious devotees, that had no clue what to do in the name of Christ. Most of them were wiped out by the bubonic plague, so that worked itself out I think. The Puritans burned some innocent people as witches, and the Protestant Reformation resulted in many Catholics and Protestants killing each other. So yes, by all accounts much blood has been shed and harm done in the name of Christianity over the centuries. These arguments already being conceded, I want to point out the difference Christians make in the world today, regardless of whether they are correct or not in their belief of a deity.
For those Christians who do a good job studying the New Testament Bible and living the Christian life, they make a positive difference in the world. Where are the atheist hospitals? A God-fearing Christian (one can live in fear of God, regardless of His state of existence) is going to be generous, humble, compassionate, truthful, and helpful to his fellow man. What are the qualities of a good employee? We want people working for us that show up on time, do their job to the best of their ability, and are an asset to the company. A good Christian does all those things. What are looking for in an employer? Someone that is fair and honest, even when correction is needed. Also a person that is forgiving and understanding, perhaps even after the time to forgiving is past. A Christian employer is instructed in the Bible to be that way. What qualities make one a good spouse? A teacher? A parent? An administrator? A leader? A servant? If a Christian is reading the New Testament and following the examples given by Jesus, he or she would naturally posses the characteristics sought in each of those positions. Christians also give of their time, money and talent to help the community, and those around them that suffer. Good Christians (and not all are, admittedly) do for others without seeking acknowledgment, compensation, or recognition. They rebuild homes after hurricanes. They give out water, blankets and food to those in need. They staff homeless shelters, volunteer in food pantries, and take the elderly to the doctor.
The world we live in is a messed up place. We’re it not for Christians, whether their faith in God is misplaced or not, the world would be even more heartless and cruel than it is now. So Mr. Atheist: Go on not believing in God. But be warned: if you discourage others to abandon faith, you’re making the world a more miserable place to live in, even for yourself. Christians are busting their butts expecting to be rewarded in the life to come; why do you care if they’re wrong? They make this life better for everyone living in it.