"The ego is the idea of selfishness."
At the very foundation of the entire ego thought system is the idea of selfishness. But more accurately, it is the idea of not sharing. It's an idea of being exclusive, the ownership of something which is considered "yours alone", and inaccessible to others.
"You had everything when you were created, just as everyone did."
God's Kingdom was set up so that everyone has everything. And this goes way beyond the kind of sharing that you experience on a physical level. In Heaven, every being has literally 100% of everything. Everyone has full access, simultaneously, to the totality of all that exists. Even your SELF is shared with everyone, as are all your creations.
This is oneness. And just because one person has full access to everything it does not shut out access to anyone else, there is no limitation, no compromise, no partitioning, no need to only access part of everything, and there is no private ownership. In reality is it possible for everyone to have everything always. You ARE everything always.
The entire idea of the ego is the idea of not sharing in this way. It's the idea of exclusivity. It's an attempt to own some portion of reality that you can call "yours alone", protected and fenced off by some kind of wall (such as the body), so that not only is your prized possession kept isolated inside the walls (such as within the body), but everyone else is also kept outside the walls (such as outside the body).
The desire not to share, is the entire basis of the separation. The ego is built on it. And this means that any attempt to have something for yourself that you want others NOT to have, or anything which is true of you and not true of them, or any sense of inequality of any kind, produces egotism. And this egotism is essentially SELFISHNESS.
The result of this selfishness is that you experience yourself as being fenced into a prison, ie the body. You see yourself as though everything which is "yours" is inside the prison. And everything outside the prison is not yours. In turn, you see that you are the only one allowed access to what is inside the prison walls, meaning that you experience yourself as being entirely alone within its confines.
This leads to the perception of yourself as though you are inside a body, you are the only one inside the body, the body is your private property, no other mind shares your body with you, you are alone and lonely and trapped inside of it, and the body's walls defend your hoard from the rest of the sonship.
This is how most people experience their sense of identity. That they are a single isolated "separated self", living within prison walls, everyone else is "outside" the walls, and nothing is shared across this boundary. The body acts then as a separation device, keeping them out and keeping you in, so that what is yours within is yours alone and your private possession.
"The body is clearly a device for separation"
From here, of course, upon seeing oneself as special, with a deeply rooted selfishness, a desire to be given special favor by God, and seeing oneself as excluded (separated) from sharing the Kingdom (exiled), so-called "relationships" with others take on the form of what we call special relationships. Basically this means that relating to others is always tainted with elements of selfishness, elements of exclusivity, elements of ownership or possession, and attempts to control and manipulate.
You see, a selfish self, ie a self that is "being selfish", has to believe that something is owned by others that it does not have access to. By cutting itself off from sharing it is able to believe in something privately hoarded and exclusive to it, but to do this it MUST also believe that others own something that it is excluded from. So now others are seen as hoarding privately hidden secret "stuff" that the selfish self wants and is jealous of, and so begins the attempts to wrestle it from others through what ultimately becomes attempted control and murder.
This is outlined in the "laws of chaos". Having seen yourself as an excluded, exclusive self, whose value is special and whose importance and truth is unequal to others, you believe other people also have something "special" locked up inside their bodies. And now you will seek to enter into relationship of some manner with them, to try to steal from the inside of their body the secret treasure that you believe should be yours.
So long as you lack what they have, you will feel an emptiness and a compulsion to steal it from them - a sense of "need" or neediness, in which you will make demands of them and place conditions on the relationship. This of course leads to conditional love and various forms of bargaining and betrayal. It can even become violent and lethal if it is strongly perceived that the other has what you significantly lack, is therefore guilty of stealing it from you, that you are justified in any action to retrieve it, and being denied it is a slap in the face that compels revenge.
All elements of this special way of relating stem from the foundation of the whole system of thinking. It all starts with this deeply rooted sense of selfishness, leading to isolation, leading to specialness and special relationships, and ultimately death.
The fundamental ONLY problem therefore is the unwillingness to share. The unwillingness to be equal. The consideration of one's own selfish made-up needs above and beyond the freedom and wishes of others. As you become presented with your own selfishness staring you in the face, you will learn to move past it and to start considering what other people want, on their terms, per their own choice, regardless of any "special interests" that you have. Once their interests become untainted by your selfishness, your interests become shared.
I should comment briefly that being "not selfish" does not in any way mean having no self, nor does it mean self sacrifice, or putting others first and you last, or any other form of inequality. It does not mean getting rid of your identity or individuality. All it means is changing your attitude, so that you are now SHARING EQUALLY with everyone, rather than isolating, excluding, or seeing to "get" something of special value "just for yourself".
"You cannot enter into real relationship with any of God's Sons unless you are willing to love them all AND equally."
Essentially our entire journey to undo the ego is simply to undo our selfishness. We have to look at this. We may be far more selfish than we want to admit to, or in ways that we had not realized. We may be more controlling than we'd like to admit. We may be claiming to put the interests of others first while secretly having needs or wants that depend on others fulfilling us in order for us to be satisfied.
To be not selfish might be what some (with ego thinking) would call the opposite - selflessness - but this can be misleading. We are not aiming here to have no self. We are aiming to SHARE, which some would refer to as joining in holy relationship. To truly think of others interests is to acknowledge that you have no needs that are interfering with being of service to them.
It means allowing and letting go and giving up controlling them. It means seeing them free from the tyranny of your control, dominance, interference, manipulation, selfish neediness, inferiority, superiority, judgement and specialness. The relinquishment of specialness is the relinquishment of selfishness.
This actually restores you to the fullness of your self, because by sharing everything you also share in all of yourself, and share all of yourself with others. You literally tried to steal yourself from God and keep it hidden. We have to open back up to allow God in and to let ourselves be visible and accessible to others, sharing fully with them and extending love with them. This is essentially a reunion with your own soul, in which all God's children share.
"The soul is the idea of self fulness."