There are verses in the B.G., I'm too lazy to pull them up right now, in which Sri Krishna compares Himself to concepts and other beings: "I am sex life which does not violate dharmic principles... among generals, I am Skanda lord of war... ". Sri Krishna is All. In His Vishwarupa (Universal Form) display to Arjuna, all beings, devas, deities, concepts, existence, known and unknown, seen, unseen, never before seen, never to be seen, male and female are revealed within Him.
I concur (I agree for different reasons, as my comments show) with Gaura Priya, Madhuri and Maija in their views. Moreover, Sri Krishna says (again, too lazy to pull up the verse), that as embodied souls, it is highly difficult to focus on the unmanifest form of God, so therefore as beings with senses, we need to experience something to which our senses and intellect can relate.