We are religious, but I think there are lots of reasons why having a large family is wonderful! My kids are great friends to each other, and we all learn so much from one another about respect, sharing, caring for one another, especially those less able, not wasting, reusing, contentment with what we already have (i.e. less materialism), frugality, baby care, witnessing healthy pregnancy and birthing (tho none of my kids have actually seen a sibling born, they have been there right after the fact), extended and tandem breastfeeding. Also, it sure does make it easier to talk to your teens about why they should wait to have sex, and they "get" the realities of what it means to have a baby. I was watching "Little House on the Prairie" today and Laura's husband made a comment to Pa about how hard it must be to raise five kids. Pa said, "The more you have, the easier it gets." And while he immediately retracted that statement on the show, I don't think he is far off. The older ones are the experiments. You don't know what you're doing, and you never will. They will always be paving the way and breaking you in as a parent. But the young ones, you relax and it's just easier. You know what is serious and what is not. (And then you have twins and feel like a first time parent all over again. LOL) But, I think for so many people that only have 1, 2 or 3 children (the ones that always tell me, "I don't know how you do it!") that they never get past that point that children are difficult for them because they are always just in the breaking new ground stage of parenting as their children progress into each new stage. Also, they only remember how difficult having an infant was without having the help of older children. When your older ones can make their own sandwiches or fetch a book and read to their siblings or fetch diapers, mama's water, etc. it really isn't as tough. When my sister started having her kids, I used to tell her that every firstborn should come with an 8 year old. Anyway, that's my perspective.
Oh, and the best reason, having kids keeps you young. Who doesn't want that?