There is no way to prove that religion causes chaos in the world. There are two main reasons for this. However, we can point to individual instances in which religion appears to have caused chaos at least in some parts of the world.
First, we cannot prove with certainty that it is religion, per se, that causes problems to occur. There have clearly been instances in which religion has appeared to cause chaos. One such example was the 9/11 terrorist attacks. Another was and is the violence in Iraq that appears to be based on sectarian differences between Sunni and Shia Muslims. However, we cannot absolutely prove that religion is the root cause of these acts. The 9/11 attacks might have been caused as much by America’s status as a superpower as they were by religion. The chaos in Iraq might be caused in part by ethnic (and not strictly religious) rivalry. Therefore, we cannot prove that religion is behind chaos, even if it appears to be.
Second, we cannot objectively balance the chaos (possibly) caused by religion with the order that religion (possibly) causes. We can argue that religion also causes order in the world. For example, people might obey the laws of society in part because they believe that God wants them to do so. If we are going to say that religion causes chaos, we must also be aware of the possibility that religion reduces chaos.
For these reasons, we can never objectively prove that religion, on balance, causes chaos in the world.