"Like in the hand of a warrior are the of one's youth." -Psalm 127:4
This one isn't going to be black and white, because I have yet to find a Scripture that explicitly says a married couple must have children. Sure, there's the mandate to fill the earth in Genesis. There's Proverbs 31 that assumes the virtuous woman will have children, because her children rise up and bless her. Paul, in 1 Corinthians, assumes that the couple will have children, because the children are affected by how the parents treat each other (7:14). This doesn't even mention the other times that women are encouraged to bear children (1 Timothy 5:14), or to train up their children in a way that's pleasing to God (Titus 2:3-5). It could also be argued that the general outlook of barrenness in Scripture is seen to be a very sad thing. Having no children is never viewed as good, as far as I can tell, in Scripture.
Alright, having said all that, I'm still going to stick to what I said about not setting up ultimatums that aren't in Scripture. I have a very special friend that would argue that it's not wrong to choose not to have children as a Christian couple, so I do have skin in the game of not wanting to hurt anyone's feelings here, or go too far. And, it also bears noting that to even begin having this conversation, we have to recognize that some couples are not able to have children or it would be a health risk to do so. If that's the case, this one isn't to be applied to you (although maybe it could be, if you think about the option of adoption).
Why Couples Might Choose No Children
Why would a couple choose to not have children (or adopt)? Everyone is going to be different, but I'd say most would choose it out of convenience. Children disrupt every part of our lives (as they should), and it takes self-denial on our part to be a parent. Disruptions include things such as the couple not being able to go on as many camping trips or vacations, the wife's career might have to be disrupted, etc. And the budget is definitely going to be disrupted! There's also fear that could hold a couple back: fear of being like an abusive parent, fear of labor pain, fear that a child might go astray. There is probably even the fear of not looking as good after birth that could hold a woman back. And lastly, the other reason I know of for choosing to not have children is just a general feeling of not really having the desire for children. The woman doesn't have a strong mothering instinct, and so doesn't see a problem with skipping that aspect of family life.
I, personally, am of the opinion that having children is a privilege and a blessing given by God. Day in and day out, it is a crazy amount of time and influence that we get to have when we raise our children. We get to show them the beauty and love of God in an extremely tangible way, not to mention the forgiveness. Of course, some children that are raised in Christian homes go astray once they grow up. That doesn't take away from any efforts we've put towards them. But, I do think that we should have high expectations that God will bless our daily evangelism efforts in their lives, and cause their hearts to warm to Him. He gives us every reason to hope that He will bless and grow the seeds that we plant for the kingdom. Beyond any sort of obligation, I'm asking you to recognize the great privilege that God gives to married couples to have children.
At the same time, with privilege comes responsibility. It is an enormous responsibility, because the idea is that we aren't just having tons of babies, but training them up to love God. But don't that stop you from entering the game! Can you imagine if Frodo decided not to take the ring to Mordor? Where would Middle Earth be? He saw the enormous task at hand, but he also saw the vast impact he could make by going on this journey. It wasn't about him anymore, but about the greater good. Sure, it will take everything you've got to do a good job with this gift of parenting, but self-sacrifice always leads to blessing when it comes to God's gifts. This is about more than what will make us feel fulfilled or what will be easiest in life. It's about taking what we've been entrusted with, and being faithful with it (Matthew 25:14-30).
When we truly understand the task, I'd think we'd be staring in awe (and trepidation) that God would trust us with influencing the next generation for His kingdom in such a deep way. The only question left is, will you accept the privilege?
For further reading on this subject, and differing opinions, check these out: