It is often said that religion gives our lives purpose and meaning that would not otherwise be there, and this is one reason why religious people tend to reject the naturalist explanations of science when science conflicts with (or is perceived to conflict with) their religious beliefs. Often, science is seen by these people as atheistic and non-purposeful.
Now it is worth noting that while science is silent on the existence or not of a deity, science does contradict some specific religious beliefs. For example, Genesis runs fairly against science, if it's taken as the literal Word of God. But religion since it does not rest on a solid evidenced-based foundation, is very flexible, and adherents are able, if they choose, to subtly alter their beliefs to synchronize with the findings of science. Going back to Genesis, an adherent could reinterpret the story to be a metaphor or simplification, for early people would not have understood it if it was more complex and incomprehensible; or, alternately, that it really happened in the way described but everything was made such that it would appear to have formed via naturalistic mechanisms, to test their faiths. But some people choose not to alter their beliefs at all in the face of reality, choosing instead to insist that the other is wrong. We see this often with the Intelligent Design movement, but I'll return to that topic in some other post.
If we had science alone and we were left without religion, some think life would be meaningless. Science can only describe those things that exist in nature, and 'meaning' does not exist in nature, and only exists by virtue of human consciousness; that is, 'meaning' is contained within the mind, not out in the larger world. Thus, science, by definition, doesn't deal with or assign meaning. But the very fact that meaning is created by human consciousness allows any human to fill the void of "meaningless existence" however they choose--even something based upon a current religion, if he or she so chooses, but which does not conflict with the evidence that nature provides. Because ultimately, those who deny reality only deny their selves. Let's hold that thought, though, and explore what meaning and purpose is given by religion.
So religion gives us purpose and meaning. I thought about this, and I realized I didn't really know what purpose this was. On the face of it, the obvious purpose under most religions is to achieve a good afterlife of some sort. This allows us to come to grips with the idea that death is an inevitable part of our lives and the lives of people we love. Sometimes people even use it to rationalize every misfortune in their lives, ascribing it to some grand plan on the part of God, a plan which we cannot ourselves envision but in which every event is progress towards the illusive, vague goal. Okay. But what kind of grand purpose requires so much death and misfortune? Indeed, I wouldn't think God would require anything particular to occur on Earth. After all, most of our earthly problems wouldn't exist if we weren't created in the first place. So then, why create humans? Taking the Judeo-Christian view, it seems like the only reason we were created was to worship God. To me, that's not such a great reason to be around. We certainly weren't created to take care of the rest of creation, when the rest of creation could pretty well take care of itself if we simply went away and since we're doing a pretty poor job of it right now. So we're left with the preparing-for-afterlife purpose. Why have a pre-afterlife, anyway? And the afterlife must be a pretty crowded place by now; and unless the world ends soon, there'll be even more people around. Then why will Armageddon come at any particular time? Is there some critical-soul-number Heaven has to reach?
But I'm going off topic here; the point is, the purpose provided by religion isn't all that impressive, even while it may help us come to terms with mortality. But since religion's purposes aren't all that impressive, and, as I mentioned above, humans are able to create their own meaning, we are not doomed to a meaningless existence if science alone is left to us. We can find meaning in our own worlds without the help of centuries-old philosophers. Are your friends and family no longer your friends and family without religion? Does the community service you take on no longer help anyone because you aren't being watched by God as you do it? Does killing someone suddenly become okay without religion? The answer to all of these is no; nothing that gives our daily lives any meaning does not depend on God. One can even find solace regarding mortality without religion, if one looks for it. Note that I am not actually arguing against religion here; I myself am still an undecided Catholic. What I am demonstrating is that meaning and purpose does not necessarily depend on religion.
There is nothing wrong with an atheistic belief. There also shouldn't be any reason for religions to oppose science, because science merely attempts to describe what actually occurs in nature, which doesn't by definition exclude spirituality or religion; however, science does rightly exclude those beliefs which deny reality, and beliefs running counter to reality are false.