Some people will wonder why the Islamists always oppose laws which restrict child marriage. Some people will say that they are pedophiles and like to have sex with children, but that is just mischievous taunting. There is a much deeper political reason behind this attitude.
When girls are married early in the life, they begin reproducing early and keep reproducing till very late. This is because of two reasons:
1. They do not have any say in reproduction, they are just too young and ignorant to do oppose.
2. They are uneducated and dependent on the male, so whole life they only reproduce and take care of children. They are not of any other use.
This increases the number of Muslims and maintains their claim of fastest growing religion.
Now if a minimum age of 17-18 is set, the girl will have no other choice but to study. If they study till 18, they may want to study further and demand other rights. This brings empowerment and negates both of the above points.
1. They may want to go further in studies and career and will start reproducing late in life.
2. They may have a career to engage them, so they will not ave too many babies in theor life.
This trend can be seen in developed world and also in fast developing countries like India, Brazil and Russia. Whenever women get more education, they tend to reproduce less.
Also, this is the same reason why Islamists kill the teachers of girls school and bomb school buildings where girls are educated.