Herman Bavinck on Eternal Generation

 Reformed Dogmatics vol. 2 ch. 6:

For if the Son is not eternal, then of course God is not the eternal Father either...Hence rejection of the eternal generation of the Son involves not only a failure to do justice to the deity of the Son, but also to that of the Father. It makes him changeable, robs him of his divine nature, deprives him of the eternity of his fatherhood, and leaves unexplained how God can truly be called "Father" in time if the basis for calling him "Father" is not eternally present in his nature.