Aren't Muslims supposed to model their behavior on that of Muhammad?
This is called Sunnah which is the study of the Prophet's life and sayings. I am wary of those who advocate it because it comes off as idolizing to me and it is clearly stated that we are not to worship the Prophet. Imitating practices that are no longer necessary or morally right in today's society is a foolish undertaking then. We can emulate the Prophet's message when it comes to relevent practices such as with the sick and needy, but trying to incorporate an archaic practice of a society centuries past is a very stupid thing to do.
We're not. We're condemning child marriage taking place today.
You really need to speak for yourself because others definitely are, on an intellectually bankrupt basis. And no Muslim in this thread isn't condemning child marriage. But like I said child marriages are a byproduct of economic depravity, not a religious basis.
Where do you find this in the quran or hadith?
Why would the Qur'an mention the attitude of society of child marriage 1400 years in the future? You are completely missing the point of the scripture if you believe it should have been incorporated within it. Like I have said,
I reject child marriage on the basis of the Qur'an.
It's a shame God can't communicate his directions clearly. But since he can't, it seems rash and irresponsible for anybody to claim to speak for him.
Perhaps there is an intention. The reason why Islam has survived so long is because while its tenants remain unyielding, it also has the ability to adapt and fit someones perceptions and beliefs. People can make Islam a part of their lives today as much as they were able to in ancient Arabia. The journey of Islam is not a stoic linear one, but a fluid one branching in different schools of thought and opinion. It is up to the person to base their beliefs on their own morality.