The positive effects of religion on the human race include bringing people together in the name of God, giving people a feeling that they are one with him and the people with whom they are surrounding themselves in their place of worship. It is highly evident that some people get a feeling of fulfillment from this.
The effect of people worshipping together is not unlike that of people volunteering for a good cause. When you are through volunteering, you have a good feeling, which can be a result of many different things, rather like the feelings you walk away with after attendance at a church service.
Another positive effect of religion is that it helps keep people from feeling fear of the unknown. There are those people who cling to religion of some kind because they cannot bear to think that this world was not made by a creator, or God. It shakes their world to think that they have been placed here without a safety net, so to speak. Would it really be that bad if creation was a result of the Big Bang Theory, or if man evolved from the monkey? What difference can either thing really mean to us in the 21st century?
Regarding negative effects of religion on the human race, the most lasting effect of religion on the human race is that it has been the cause of almost every war since the beginning of time. With one religion thinking it is the "true" religion over all others, what other result could there be?
Another negative effect that has certainly loomed over mankind from the beginning of time is the fact that man created religion to control the masses. When religion actually started to become organized with more than just a handful of followers, edifices called churches, mosques, and synagogues were erected where people would go to worship a God they were told existed.
This God was never a very forgiving one; most followers were made to fear God, causing doubt about almost every aspect of their lives. Thus religion began to control everyone by telling them what they could do and what they couldn't do. They were even told that certain actions were "sins" and what the retribution would be (hell, not heaven) if they did not strictly follow the teachings of their religion. People unknowingly became victims of group-think.
To this day, religion for the most part is still based on fear.
Although there are millions of people who are followers of some type of religion throughout the world, it is important to remember that there are both positive and negative effects on the human race because of religion, and everyone should be respected for their belief system and not be judged or persecuted because of it.
In a perfect world, that would be the case; but as we all know, this is not a perfect world.