If there were no religions in the world, the world would certainly feel very different. There would have been a total change in the ways we see some things. There would not have been any explanation about the nature of man and some realities of this world, or we would have been forced to believe anything.
For instance, most religions have almost the same stories about how this world came into existence. Also, our society would have looked very different because a lot of other things would be influencing society. Religion is more or less a factor or a determinant about how a society would look like.
For instance, Christianity, as a religion, has various teachings that have helped in shaping any society that promotes religion. Those countries that have Islam as their religion would have looked very different because there are certain things about their religion that make them look very different. Also, what constitutes the belief system of man would be totally different.