Attempting to take your self closer to the truth in any way, will be met with ego resistance.
The ego itself is nothing, just a "way of looking" which is the opposite to seeing the truth. It distorts everything and makes everything seem the opposite to what it is. It inverts reality. It changes God into death/evil/murderous. It sees Holy Spirit as an enemy. It sees the truth as a threat. And it does not want anything to do with this idea of "waking up and not having an ego."
The ego by itself doesn’t do anything. The problem is that YOU have taken it on AS IF it is your own Self. You regard IT as the same thing as your identity.
What that does is it causes you to perceive WITH it, through it’s eyes. You then will see things the way the ego sees them.
So if you are "tied to" an ego identity which wants absolutely nothing to do with truth, cannot exist in the truth, and sees the truth as proof that it does not exist, then "YOU" will become very threatened by approaching the truth.
If for example the truth says, there is no sin, and the ego believe that sin is real and true, and therefore sin is your *identity*, to your sense of self this will SEEM to say "I do not exist."
Regardless of the fact that you may have sided with an insane ego, you do not RECOGNIZE it is insane. You think it makes perfect sense. It seems logical, sensible, rational. You will also want to defend it as though to do so is defending "your" life, because you think it is you. Therefore it makes sense to you to AVOID the truth at all costs.
The ego sees the truth as attack, vengeance, evil, warring, deadly, hateful, loss, non-existence, etc. If you identify with the ego, you will also see the truth as meaning this.
So then, you will attempt to reach out to the truth, to become closer to God, to go into the light, but because part of you is STILL holding onto the ego and is using it to perceive, that part of you seeing with the ego will think you’re trying to kill yourself.
No-one in their "right mind" would go against what seems sensible and true, and expose themselves to what must be the END of themselves. The truth is the end of the ego, and if you believe it, it means it’s the end of your self. Approaching the truth WITH the ego, pulling it along with you, is nothing short of you SCARING THE CRAP out of yourself by exposing yourself to your worst enemy, complete with no defenses.
This is the sole cause of all ego rebounds and resistance - the mis-perception that welcoming the truth is welcoming your own death. No-one wants to do this. IT seems sensible to protect yourself and defend yourself against this. In spite of your best efforts to "become more spiritual" by opening up to the light of truth, or to love, the rest of you - still perceiving the opposite to the truth, will fear out when you try to do it.
What can even happen is your ego self will create DEFENSES AGAINST THE TRUTH, which it thinks are *needed* in order to protect your "self". Or to put it another way, you who are identified with the ego, interpret the truth as your mortal enemy, and do not want it, are threatened by it and want to "naturally" defend yourself. In the name of preserving your own life, you will erect DEFENSES psychologically.
The only ego defense is *separation*, attempting to create a gap or sense of "distance" between yourself and the threat. Implementing this is an attempt to shut out the truth, by implementing a BLOCK. The purpose of this block is to block your awareness of the threat, because if you are not aware of it, to you this is practically the same experience as though it does not exist. You use DENIAL to hide the perceived danger from yourself, so you can enter an *illusion of safety*. This illusion of safety, this block, made of guilt, shows up as SICKNESS. Sickness is a defense against the truth.
The purpose of sickness then is to defend you against what you think is going to hurt you. But to implement it, you actually HURT YOURSELF. It should be obvious why this is insane. Perceiving your best interests through the filter of the ego is insane, because it shows you the *opposite* of what will actually help you. What would really help you, and what is the UNDOING of sickness, is to correctly perceive WITHOUT the ego, that the truth is NOT a threat or hurtful, is FOR you not against you, is welcome, you want it, and it does NOT mean you will not exist.
When you can perceive correctly that you are not being threatened by the truth, you will UNDO the NEED for the defense, and this will make the sickness *disappear*. Literally. All symptoms will be dropped, because you have no further need for them. Sickness is always serving the PURPOSE of being a defense to keep you safe, even though it does the opposite. Without its purpose, it will not exist because you will withdraw your belief from it.
Essentially, approaching the truth is going to make your ego-identified self threatened. It will want to defend itself and it will be horrified, offended, upset and scared of the truth. This can lead people to BECOME SICK by doing the course. It can also cause peoples lives to turn upside down, as reactions to the misinterpretation of the truth.
Gradually the way to undo this is the development of trust and coming to perceive correctly WITHOUT the ego’s interpretation. This will naturally lead to a WILLINGNESS to accept the atonement, and accept God’s truth as true. And then you will have no resistance whatsoever. It is only your beliefs to the contrary that try to defend you against the truth.
So each time you have an ego rebound, don’t belittle yourself or judge yourself as failing to do the course right. I used to think I was making big mistakes when I had rebounds, like I was guilty for having them. But I had to learn to be gentle and acknowledge what they were saying, recognizing it was a part of my SELF that was afraid and offended by the truth I was opening up to. It’s perfectly okay to take a BREAK from pushing yourself towards the truth, to let your ego settle down a bit, and integrate what you’ve learned so that you can move forward with more willingness and less fear.