I definitely know that atheists and the irreligious enjoy life unless they choose not to. I certainly do enjoy mine. In fact, I was only able to enjoy life after I said goodbye to religion. I was brought up in a home that was very rarely religious, with emphasis on schooling and knowledge, rather than belief. I didn't understand the value of such upbringing until I tried my hand at christianity for 7 long years from the age of about 14.
It all started when I changed schools to a christian school in a town far away from my home. The schools I have been to before were very much secular and didn't have any religious elements. However, this new school had a small daily prayer gathering in the hostel, led by students. Out of curiosity I asked my friend who attended it and he invited me. I went, and in the room I just followed what everyone does. I got a small new testament bible and became a regular at the meeting.
Soon I learnt that they also go to church on Sundays, and apparently the church is led by our correspondent (highest authority and owner of my school). I joined that too, and once even witnessed an immersion-based baptism (or something like that). There was also a larger weekly gathering in school which I attended, which gave us opportunities to "confess sins and repent".
Anyway I stayed in that school for 3 years, being as firm a christian as I can for a good part of the time. Then I shifted to another city. The hostel here was more religious as everyone staying, regardless of personal beliefs, have to attend church. My atheistic roommates and friends scorned how they had to put up with what they called "nonsense". I on the other hand was wondering how I can "save" them by the grace of "my lord jesus christ" since I was a quiet person and was afraid to talk to people who don't agree with me.
Recalling, I had been one of the top performers in the secular schools I studied. But once I changed my education to christian schools, my performance began to drop slowly. I'm still better than the average, but not the top. Apparently the atheistic friends I had would perform better than I ever could imagine myself performing.
Anyway 2 years in the school, I continued trying to be strong in my faith. Then about a year I stayed at home before going to a different country for further education. Problems were caused at home when I revealed my belief in jesus, as my mom is atheist and my dad pretty much is too (with occasional bursts of hindu faith). I desperately wanted them to see how much my faith meant to me and to see them accepting jesus as well. (How foolish I was back then).
After going to a different country, my faith began to get its knocks as I thought about how it's affecting my life. At first I found a church and attended it. I tried to pray whenever I can remember. Then I realised slowly that it's not worth being a christian. It's like being in chains.
Being a christian is like being in chains. The bible and the church is telling you that we are all sinners, committing sins everyday, so we must pray and ask jesus to cleanse our sins from our souls. I felt guilty of sin for almost everything. It's very usual for girls to wear revealing clothing in this country, but I would feel so guilty and ashamed to set my eyes on them even without intention, that I wish I was blind. Didn't jesus say that if you look at a woman with eyes of desire, you have already committed adultery with her?
I had the guilt of not doing things also. I would hate myself for not being a good christian, not doing daily prayers, not reading bible. I would scold myself that I can't talk to my friends about jesus and save them from hell. Though I had never physically hurt myself out of guilt of sin, I had been mentally torturing myself.
Slowly I realised that I'm in pain for the sake of my religion. I want to break free of the chains. So I decided to drop everything, to stop believing in jesus, in sin, in hell and all the christian stuff. I really felt free and able to enjoy my life. I read books that helped me better understand certain aspects of human psychology. I no longer felt guilty to look at girls dressed sexily. They do so because they want me to look! As long as I don't attempt anything wrong upon the girls, I'm not guilty of anything. (The girl example is just one of the several things I became free to do).
I didn't immediately let go of the belief that there is a god. It took me a while to go from theism to pantheism to agnosticism to atheism. But I don't call myself atheist. Buddhists are atheists too. I call myself irreligious because I refuse to subscribe to any religion or belief system. I only accept what reality really is. I have learnt that I could be wrong, and I should be ready to be corrected. I have learnt that science while it may not have all the answers, those that it provides is based on the observable reality around us and not on the words of a book.
Now I enjoy my life very much, a lot more than a religious person can ever imagine to. I am not restricted by anything except the law. Besides it, I set my own rules, but it doesn't mean I do whatever I want to do. An irreligious moral system is to be guided by consequences. I learnt that consequences are a better moral compass than a holy book. My actions have consequences, and I determine what I do with regards to the consequences it will bring. That's why I enjoy life.
Update (6-Sep-2011, 6:02 am): It has been more than a year since I originally wrote this post. While most of it continues to hold true, I now call myself an atheist and I'm not ashamed to be one. Being an atheist simply means to not have any belief in any form of "god" or gods. In that sense, I am an atheist, and denying that is not going to help me in any way. I continue to stand by my view that an irreligious or atheistic moral system is guided by the consequences and implications of my actions. An eternal reward/punishment system is not necessary to motivate me to be good, as I choose to be good for goodness' sake and to selflessly serve others.