Questions on the Trinity for Muslims - Let's start very simply. Could Allah have a finger?
Shi'ite Muslims call 'Ali the finger of God. Now the term "finger of God" is not meant physically, but as an expression. While a finger is distinct from the rest of the body, that does not mean it is separated from the body, it is a different body, or that you have more than one physical body. Likewise, nothing restricts God from having three distinct parts, yet with no separation. Saying that God has a finger, part, or spirit, does not mean there is more than one God.
Thus, when speaking about God in human terms we must be careful not to jump beyond what a metaphor is saying.