The Ruling on Studying in Mixed Universities in Order to Call to Allah
Question :
Is it permissible to for a man to study in a university in which men and women mix in one place, bearing in mind that the student has an active role in calling to Allah?
Answer:
It is my view that it is not permissible for a person-man or woman to study in mixed schools; this is because of the great danger to his modesty, reputation and morals, because a human being, whatever may be his reputation, morals and innocence, if there is a woman sitting next to his chair and especially if she is beautiful and revealing her beauty is unlikely to be safe from temptation and evil and everything which leads to temptation and evil is forbidden and is impermissible. So we ask Allah, Most Glorified, Most High, for our Muslim brothers that they protect them from such matters as these which bring nothing but evil, temptation and corruption to their young men. And if no other university is found except this one, he should leave his studies in order to study in another country in which there is no such mixing. So I do not consider it permissible, although someone else might hold another opinion.
Source:
Ibn 'Uthaimin
Fatawa Islamiyah, Vol. 5 Pages 163-164