But if the "prolepsis" of justice or gods did not exist, we would never begin considering or discussing those concepts in the first place.
In similar fashion we could argue that if prolepsis of unicorns did not exist, we would never be able to talk about unicorns. Unicorns, justice and gods are complex concepts that we understand by the act of reasoning. Pre-concepts are simple patterns - building blocks which are used by the act of reasoning to create complex concepts. Prolepsis of gods or prolepsis of justice is an oxymoron. It's like saying simplicity of complexity.
We can talk about unicorns easily because we combine plethora of patterns we can merge by the act of thinking to understand unicorns as a concept. In similar fashion we can easily talk about 'duocorns', 'tricorns' or 'quadrocorns'. No-one reading this post has ever heard about such creatures but everyone can easily imagine these because everyone has developed sufficient amount of patterns to be able to comprehend such complex concepts. The same process applies to justice and gods.