When Lucifer said “I will be like the Most High. I will ascend” and etc. it says that a 3rd of the angels plus the Devil were kicked out of Heaven. How is it possible for a Revolt of that kind to take place in Heaven?
If free will is possible to that extent for some angels or all, is it possible for any Spirits of people who have not been assigned to earth yet to revolt as well? In other words, people like you and I that exist in Heaven who have not yet had the opportunity to be born in the flesh yet. How could any evil have existed in Heaven in the pure presence of God to begin with?
You’ve posed several theological issues here but let’s deal with the most important one first. The Biblical view is that life begins at conception. (Psalm 139:13-16) The notion of a spiritual pre-existence comes from Mormon Theology. If you’ve been brought up in that tradition, then your entire view of Heaven is far different from that of traditional Christianity.
Angels are a totally separate order of creation, distinct from humans. The reason that fallen angels are in everlasting chains awaiting judgment (Jude 1:6) is that they crossed the boundary into humanity by taking on human form. The idea that there are spiritual beings in heaven awaiting assignment to a human existence would seem to blur the distinction as well. In any case it can’t be supported in Scripture.
In speaking of the revolt in Heaven, the Bible only says that Satan was created as the model of perfection, full of wisdom and beauty until wickedness was found in him (Ezekiel 28:12 & 15). Apparently this wickedness gave birth to the pride that resulted in his desire to become like God as stated in the Isaiah 14 passage you quoted. The revolt that followed was the beginning of his ongoing attempt to fulfill this dream.