Actually, what may be "obvious" to one may not be so "obvious" to another and just like blanket condemations - observations can sometimes come back to bite one in the buttocks.
Tell me, if someone is bothering to read FreeRepublic, do you really think a worry of them being THAT obtuse is credible?
Sometimes people can be committed to helping each other but are not exactly competent. This can be a problem too.
Spirituality comes in , becasue people that go to church tend to spend at least a little time in self inspection. They are open to the fact that there might be issues in their life that need correcting. So people that go to church and are spiritual tend to also be more reponsible.
In summary, marriage needs both people to be committed to the interests of others in the family, marriage needs competence, and these things generally don't happen without spirituality.