The ego is a belief that you are sinful and guilty. It really believes this is true. It believes in attack, that it has attacked, and that therefore it is sinful, is due for some punishment, and someone is going to deliver it.
When YOU, who are not the ego, are identifying yourself with it, and are confused in believing that what applies to IT applies to YOU, you will experience whatever applies to it.
So if someone comes along and attacks or targets "you", this will be an attack on the ego. The ego will believe it is real, and valid, and justified, and that it is the truth about you. The sin and the guilt that it believes in makes the attack real, and produces effects within itself. Thus it is vulnerable, and seems to suffer and feel hurt.
When YOU, who are not the ego, are identified with it, when it perceives attack, YOU will also experience what the ego is experiencing. Therefore you will perceive that YOU yourself are actually being attacked, because you are sinful and guilty. Your ego sin and guilt will fly up in your face, you will be upset, hurt, and perceive that you've been damaged. But you're only able to experience this because you are aligned with, attempting to be one with, the ego, and to share in its perspective. However, YOU are not the ego.
What YOU are, is a being, a mind, which is able to choose to either align itself with God, or pretend to align itself with an imaginary mind - the ego. But who you are, is not really the ego, and can choose to unalign itself from the ego and return to alignment with God.
When you do this, through forgiveness, it entails that you come to the awareness that sin is not real, which therefore means that you are not really guilty, and need not be afraid. Who you ARE, is not the ego collection of thoughts and beliefs that are composed from sin/guilt/fear. Instead, if sin is not real, then separation can't have really happened, the events that led to the guilt cannot have really happened, therefore the sin and guilt are invalid. They cannot apply to you, define you, represent you, describe you, or modify you to fit them.
If you can see that YOU do not have to be defined by the ego, and do not have to stay associated with its thought system, you can come to recognize that you are innocent. God's truth describes you are innocent, always loveable, already forgiven, and completely invulnerable to attack. It also gives you the recognition that the ego is nothing more than an illusion, because sin and guilt are illusions. They aren't real.
This means you now realize that you never really were guilty, never really can be guilty, and sin that could possibly ever prove your unworthiness cannot be true of you. You simply have not sinned. Therefore YOU are not made of sin, and you are not made of guilt. That's the same thing as saying, you do not really have an ego. And that also means, you therefore cannot be targeted or attacked in the way that the ego attacks itself through belief in attack.
It is not that you have to do anything special to the ego to defend yourself against it. It is not that you need a special barrier of protection. It is not that you need to constantly put in effort to maintain a certain kind of thought system in order to not slip up and allow attack to get you. Rather, when this all becomes clear, that you are not sinful at all and never really could be, and that God sees you as PERMANENTLY INNOCENT, your identity can no longer contain "ego".
So now, when someone comes along and they do some activities that you previously would've thought of as an attack, and reacted to, there won't be sin and guilt in you. You will know through experiential fact that you are permanent innocence, therefore any claims by anyone that you are sinful or guilty or unworthy or worthy of attack MUST be false. They simply cannot apply to you.
So when someone claims "you are guilty" in some way, what they're really saying is "you are made of guilt", and this is not true. So they're referring to someone by the name of "guilt", and it's not you, because obviously you're innocent. So they're not even talking to you. Your name is innocence, and you will only respond to confirmations of your innocence.
Any reference to a guilty person cannot be a reference to what you are, therefore it does not even REGISTER with "you" as being about "you", because it's not. Your identity is not what they are targeting. You suddenly realize that they are apparently targeting SOMEONE or SOMETHING, but it's certainly not YOU! And since nobody else is around, it is clearly obvious they are actually just having a spazz and attacking themselves, projecting their own guilt all over the place believing it applies to you. And there you are, invulnerable, bullets bouncing off left and right, because you are inaccessible to the idea of attack.
What becomes clear, simply through clarity alone, with no need to have any thoughts about it or interpretations or it or special treatment of it, is that... simply.... in all truth and clarity, when you are sane. ..... the ego simply is not real. Attack is not real. It cannot and does not do anything to you. It only ever seemed to do something to a sinful guilty self, which is no longer what you are. And never were.
The ego, when seen with True Perception and perfect clarity, is RECOGNIZED as being 100% illusion, 100% not the truth, 100% artificial and unreal. Therefore it is simply just clear, and obvious, that it does not apply to you. It can do nothing to what you are. What you ARE is perfect innocence, holiness, immortality, eternal life. You ARE as God created you. There is not a single illusion that can ever claim anything true about you and therefore can never apply to you. And knowing this, you have the peace of God.
Illusions cannot assail the Kingdom of heaven. The ego will never enter it. The kingdom is perfectly protected without any defenses by the sheer fact that all attack is not real and does not apply! It's just simply the truth. The truth is safe from all lies and all corruption. This is why you are forever immortal, forever safe, forever innocent, and if you will let go of your false sense of identity as "sinful, guilty, afraid", you will experience an invulnerability that you never thought was possible, and which is completely void of any trace of vulnerability or susceptibility.
You cannot be attacked because you are not attackable, because attack is not real and it does not apply to those who are innocent.