Prenuptial agreement and financial stability be damned, it is the soul of the spouse and their eternal destiny, that is what matters.
Your idealism is nice, but it has no practical application. Explain to me how a husband has ANY influence on his wife's salvation, if she is incentivized by the State to destroy the marriage, steal the children and get paid for it? Once she's gone, you have ZERO influence on her life and VERY LOW influence on your children's as well. All you're left with is prayer (which prayers, no matter how good, cannot affect free will, which your wife used to destroy the marriage). So all your spiritual sentiments sound lovely, but they are meaningless, practically speaking.
The purpose of the whole prenup debate is to ADD PRACTICAL, REAL-LIFE CONSEQUENCES to DIS-INCENTIVIZE a wife from leaving. (The husband already has dis-incentives to leave, because he'll lose his children and most of his money). Without any consequences, all a husband can do is "hope and pray" his marriage doesn't end due to a frivolous or emotional reason by his wife. Prayer alone does not solve every problem.