What is the ruling on remaining in schools where students talk about homosexuality and mock God and His Messenger, given a desire for jihad and to depart from this worldly life?

You must be keen to choose righteous friends who will help you in obedience, keep you away from sin, and encourage you to call to Allah. You should also try to guide your colleagues, and remember that for Allah to guide a single man through you is better for you than red camels. Furthermore, you should forbid your colleagues from mocking Allah and His Messenger, for that is disbelief. If they do not respond, inform the administration about them, and do not sit with those who disobey Allah at the time of their disobedience.