The Father of God

Just got a great argument by listening to the Dividing Line Program and the look on Dr.White's face when a caller identified a question he got from a Jehovah's Witness(Yes Not my own argument but a good one none the less) Dr. White was asked the question or given the comment which goes something like this. (The Father is never called the Father of God) Which would be their exact argument In contrast to Jesus being called the son of God which they use as a term of divinity. Think about it?