Seeing there we would already have an issue
Being married doesn't make one a good parent unless you honestly believe that atheists who in many cases ain't married are worse than them? Also, married people get divorced for whatever reason, so wouldn't that be a demonstration of the failure of the initial assumption that being married ought to be a requirement?
What about a homosexual couple, is there any documentation that they are worse parents than a standard couple?
Something like this (the general idea) would end in complete chaos and civil war, with people disagreeing