At its heart the ontological argument has us imagine a horizon of “greatness” and “perfection.” The argument then goes on to say that existence must be, necessarily, a part of that vision. Maybe, maybe not. But in one sense it really doesn’t matter. Because I think that horizon of “greatness” and “perfection” can do much of the work we want from any conception of God, with or without existence.
For example, when I think of “the Kingdom of God” what I have in mind is an ideal, a biblical ideal, a place where swords are beaten in plowshares and where the lion lays down with the lamb. Once posited, this ideal creates two eschatological functions, one negative and the other positive.
Image source and article: http://experimentaltheology.blogspot.com/2013/08/the-ontological-argument.html