Ethers determine who you are in the same manner that clothing and uniforms tell people who you are. When you are part of God's heavenly ether, your entire body functions differently. For example, you may not bruise easily, but a deep cut may take longer to heal. Your digestive system may slow down so that you are not experiencing hunger pangs, and your teeth may suddenly brighten. Living in God's ether is not ideal for someone in the earth realm, but it renders the person immune to Satan.
Being immune to Satan does not mean that the person will never commit sin, but if they choose not to sin, they have the capacity to resist. They can say "no" to even the most tempting reward being offered by him. Angels exist in God's ether from conception, through childhood and into adulthood, and remain in that ether unless they commit an act of betrayal. Acts of betrayal include blasphemy and promoting the works of Satan such as engaging in witchcraft. Angels who commit acts of betrayal immediately exit God's ether and remain in the earth's ether until they face judgment.
Human beings also can exist in God's ether but the process is different. Humans who exist in God's ether have gradually achieved a very high level of spirituality by consistently resisting the temptation to sin. The person's ether becomes purified of the accoutrements of sinful thoughts, words and actions, and eventually approximates the purity of heaven's ether. Some people have been able to achieve a purity that approximates heaven's ether by withdrawing from society and assuming a perpetual meditative state. The test of whether someone has genuinely become purified is whether they can maintain that state while engaged in ordinary life. The further test is whether or not they have a consciousness of God that gives meaning and purpose to their perseverance.