The issues that we as Christians can unite with Muslims on are first our common spiritual history beginning with Father Abraham. The teachings that connect Christianity, Islam, and Judaism are the belief in monotheism. That there is One Supreme Being that is the ruler of all creation. This is a great point of commonality that brings solidarity in engaging with Muslims.
The second, matter that is a gateway to engaging with Muslims is that both of our faith teaches one to live a moral life. The emphasis on commandments and spiritual practices produces a righteous atmosphere that benefits all humanity. This should never be forgotten.
Lastly, our defense against a common enemy unites us. The enemy of hedonism and a society devoid of respect for God and His creation. These issues are ones that should cause Christians and Muslims to want to dialogue and seeks ways to work together. By linking arms and arms to these three issues above, we can advocate more good in the world.