This is a very interesting topic, and one I'm glad to see being discussed here. I feel that having children, or not, is a very personal decision that is all-too-often not given the due consideration it deserves. I myself am 25, single for the foreseeable future, and childfree (CF).
A variety of factors have gone into my decision to be CF. For one, I have various medical conditions that would make pregnancy extremely difficult and dangerous for me, and that would not be something that I would want to pass along to a child, and that's not taking into consideration any issues contributed by a future husband. (There are other issues which I won't include at this point, but am willing to discuss here or in PM.)
I am also very tokophobic (fear of pregnancy and/or giving birth), and have been from a young age, and for a while had plans on adopting if I ever were to have children; I have since decided that I do not want any, either way. I am all for adoption, though, and wish more people would consider it as an option.
I am a very introspective person, and many, many hours over the course of several years have been spent in personal examination, contemplation, and prayer about my decision to be CF. This is my own decision, and not one I would ever press on anyone else. When I am done with my educational process, established in my career, and finally have time to date and eventually marry, this decision will also affect my choice in future husband, as I have no desire to have a relationship with someone be or become unhappy with resentment toward me for not giving him children or trying to.
That being said, I love children. I have a future membership in the group of aunts/uncles who will take the children of friends and family out for the day, have fun, get them all sugared up, and send them back home to mum and dad. I will totally do Sunday School classes, arts and crafts, storytime, and whatever else.
I will find almost any excuse not to go to social functions when I visit my folks at home. I come from a small, rural community, where I am seen as more or less a freak for not being married(or not) with multiple children and living within a short drive of my 'rents; that I want to have a professional career in architecture is almost unheard of.
Thankfully, right now, I'm still getting away with going, "Oh, haha ....... um," and never answering properly when neighbors start asking when I'm going to start giving my mother grandchildren (note, my community is one of those with an inordinate number of single mothers around my age; more often than not, they don't even ask when I'm going to get married before asking when I'll have children).
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Some resources:
Christian Childfree blogs/forums/communities:
http://twiga92.wordpress.com/on-being-christian-and-childfree/http://cf-christians.livejournal.com/Secular forum:
http://www.thechildfreelife.com/forum/index.php