Can Muslims call God "the Father", and do Muslims and Christians worship the same God

Answer

No, God cannot be called "the Father", neither literally nor metaphorically -- this is part of why Surah al-Ikhlas ("Say, He is Allah, One...") was revealed. Muslims do not say they worship the same God as Christians in the sense of sharing the same conception, since the Christian conception of God differs; nor do Muslims accept the Bible's depiction of Jesus worshipping "the Father" -- in the Islamic account, Jesus (peace be upon him) referred to God as the one true Deity who creates and sustains all that exists. There is only one true God: the One who begets none and is unbegotten, who created the heavens and earth and everything in them, who is one in essence and cannot be composed of parts, and to whom none is comparable. Muslims worship this one true God; Unitarian and Christadelphian Christians share this conception too, rejecting the trinity and the divinity of Jesus. But the majority of Christians worship their own contrived conception of God. So in the sense of having different conceptions of God in their worship and devotion, yes, Muslims and Christians worship different Gods -- though in a deeper sense, there are not two different Gods to be worshipped: one worships the One true God of all that exists, and the other worships a concocted notion of God that does not exist in reality.