Ego is a device for separation. It is like a stained glass window made of many fragments and different types of filters. Each colored panel obscures and distorts the light behind it and changes it, filtering out what it does not want to see.
When the ego attempts to hold itself up to the light of God, to heaven, to creation, and attempts to look at it, it looks through this stained glass window. It CAN ONLY see separations. It is INCAPABLE of seeing unity. It thinks it is objective and impartial and unbiased but it is absolutely incapable of ever seeing and recognizing the nature of Oneness correctly.
All it sees are separations, partial truths, information which is left out and distortions that have been added. It is literally impossible for it see oneness, wholeness, truth, or consistency.
When the truth of Heaven is that God creates and has many sons and they each have individual free will, the ego looks at this through its stained glass window. All it sees is, oh look, there seems to be a correlation between the different pieces of glass and the idea of "many sons".
You can be sure that, if the ego ever looks at Oneness and sees something CORRELATING to its way of looking, that it is seeing separations, you know that something is UNTRUE. The ego cannot see God and understand it. If it is seeing something "in" God and saying, that it matches up to how the ego sees in fragments, IT IS NOT SEEING the truth.
All we can say for sure is, the ego can never see God correctly, cannot understand Oneness correctly, cannot comprehend how God has many sons without it being a separation, and therefore we need to TRUST and have FAITH that God's many sons is a truth the ego will never accept.
We are to accept the truth as it is presented. The course is telling us God has many Sons. Jesus is not a liar. Therefore, it's telling the truth. And somehow, all of those sons are "one", yet still distinct with individual free will. We have to simply accept this is true even if our egos don't understand how.
"To know reality is not to see the ego and its thoughts, its works, its acts, its laws and its beliefs, its dreams, its hopes, its plans for its salvation, and the cost belief in it entails."
"Where there was darkness now we see the light. What is the ego? What the darkness was. Where is the ego? Where the darkness was. What is it now and where can it be found? Nothing and nowhere. Now the light has come: Its opposite has gone without a trace. Where evil was there now is holiness. What is the ego? What the evil was. Where is the ego? In an evil dream that but seemed real while you were dreaming it. Where there was crucifixion stands God’s Son. What is the ego? Who has need to ask? Where is the ego? Who has need to seek for an illusion now that dreams are gone?"