Sometimes, due to time or money constrictions, couples will choose to begin with a smaller, civil ceremony. Then later on when they have a bit more money to spend, they will then go through and have a much larger ceremony and reception on an obviously much larger scale. Although a good number of weddings will have many religious components, there is also quite a fair amount of weddings that will have no mention of religion whatsoever.
Another major reason why a couple will have a civil ceremony instead of a religious ceremony is that they will have a general marriage ceremony without any religious connotations whatsoever. This is a great idea for couples that actually have different beliefs or religious backgrounds. With a civil ceremony, there will never be the chance of any arguments over what religious segments should be put into the ceremony and so on.
Instead of having your wedding in a church, you can always rent a space for both your ceremony and the reception. Your obvious choices will be beautiful banquet halls, ballrooms, gardens and so forth.