Here is a link to lots of IDF films which give evidence of the uses Hamas makes of civilian institutions and structures. To use a civilian building as a military base, to shield your forces and equipment by placing non combatants in the way is a direct contravention of international law and allows for defensive actions against these locations as legitimate targets.
The civilized rules of conduct however are exactly that. The consequence of centuries of experience of conflict and how to express it with the minimal horror and loss of life and labor. Islam however, is anti civilization. It’s methods in war demonstrate contempt for any system which enhances life. Hamas is an Islamic organization which very recently implemented some of the most harsh aspects of sharia law such as amputation and crucifixion. When one protests on behalf of Gaza, Hamas and other Islamic organizations, one should ask oneself how life would be for you under it’s rule.