This will be the final installment on the SAHM issue, though I will continue to do a few more entries following up on the gender series.
Having argued that is is not a biblical command for women in general, and mothers in particular, to stay at home, though it very well might be sin, I would like to ask the question, "What about stay at home dads?"
If it is a matter of Christian liberty whether or not a woman stays at home, does the same go for men? Can she work and he stay home?
I would say two things; I don't think it is sin, but I would not recommend it in general.
There are certainly cases where I could see this being helpful, but I would not begin there. I would recommend that if the family feels led to have one parent stay home, outside of some extenuating circumstances, it should be the woman.
Why? There a handful of principles that cause me to lean this way. Please do not read any of these as though each were a "nail in the coffin" argument. These are a number of factors that, when taken together, lead me to not recommend the man stay home.
First of all, there is the biological factor. Women are physically designed to develop babies in their bodies, birth them, and nurse them. Historically, this has been a strong determinant for women to stay home, particularly in days when the physical demands of pregnancy were not able to be mitigated with technology and medicine. Months of pregnancy, traumatic births, and years of nursing, tethered women to their children and the home. Certainly, much has changed in the past century and many of these challenges have been alleviated. Pregnancies and births are much safer, and nursing is not even necessary. Nonetheless, the biological factor has not been completely erased. Feminism has known this and therefore has been a strong proponent of abortion being legal. Why? Because they see that women's biology limits their mobility and economic freedom. Get rid of the baby, get rid of the chains.
Second of all, there is the temperament factor, which I believe is at least partly tied to the biological factor. There are certainly exceptions to the rule, but experience has taught me that women are more nurturing, particularly with small children. Why is it that there is an astronomically higher number of single moms than single dads? Because women are far less prone to neglect the child they have carried. They are knit together in a special way, and this knitting provides a foundation for nurture that, in most cases, men cannot match. Again, you can find very nurturing men, and women who are horrible to their kids, but I am talking about general principles.
Last of all, there is the spiritual factor. I argued in the gender series that, according to complementarian theology, it is the role of the man to initiate flourishing through loving leadership, and the role of the woman to maximize flourishing through loving submission. As a leader, it is the responsibility of the man to carry the burden of risk. The reality is that the world is a dangerous place. Certainly the west is safer than most of the world has historically been, but the dangers are not gone. Historically, this has been another reason women tended to be more homeward oriented. Men don't stay home while the women head to the front lines. You may think I am making the world out to be more dangerous than it is, but I would challenge you to read statistics about violence, rape, trafficking, etc.. Furthermore, with the advance of globalization, multiculturalism, and the decentralization of warfare, I would argue that the Pax Americana is eroding. Again, I am not saying that because of the danger of the world, a woman should never leave the house. I am saying that given these factors all weighed together, I would lean away from the man being the stay at home parent, and would strongly encourage the woman to fill that role.
Feminists look at the historical tendency for the woman to fill the stay at home role and cry "patriarchy, control, abuse"! I look at the situation and chalk it up to wisdom. Man certainly has sin, but the entire image of God has not been erased. There are plenty of broad cultural tendencies that exist, not because of distortion and abuse, but because of common grace. I believe that cultures throughout time have intuited the factors I have outlined above. And I believe that to try to reverse the trend would not lead to human flourishing, but rather create unnatural and unhelpful patterns.
I would repeat, there are always exceptions to the rule, and perhaps you are in a situation that requires exception. God bless you, I mean no offense.