Question: "How, why, and when did Satan fall from heaven?"
Answer: Satan’s fall from heaven is symbolically described in Isaiah 14:12-14 and Ezekiel 28:12-18. While these two passages are referring specifically to the kings of Babylon and Tyre, they also reference the spiritual power behind those kings, namely, Satan. These passages describe why Satan fell, but they do not specifically say when the fall occurred. What we do know is this: the angels were created before the earth (Job 38:4-7). Satan fell before he tempted Adam and Eve in the Garden (Genesis 3:1-14). Satan’s fall, therefore, must have occurred somewhere after the time the angels were created and before he tempted Adam and Eve in the Garden of Eden. Whether Satan’s fall occurred a few minutes, hours, or days before he tempted Adam and Eve in the Garden, Scripture does not specifically say.
The book of Job tells us, at least at that time, Satan still had access to heaven and to the throne of God. “One day the angels came to present themselves before the LORD, and Satan also came with them. The LORD said to Satan, ’Where have you come from?’ Satan answered the LORD, ‘From roaming through the earth and going back and forth in it’” (Job 1:6-7). Apparently at that time, Satan was still moving freely between heaven and earth, speaking to God directly and answering for his activities. At what point God discontinued this access is unknown.
Why did Satan fall from heaven? Satan fell because of pride. He desired to be God, not to be a servant of God. Notice the many “I will...” statements in Isaiah 14:12-15. Ezekiel 28:12-15 describes Satan as an exceedingly beautiful angel. Satan was likely the highest of all angels, the most beautiful of all of God's creations, but he was not content in his position. Instead, Satan desired to be God, to essentially “kick God off His throne” and take over the rule of the universe. Satan wanted to be God, and interestingly enough, that is what Satan tempted Adam and Eve with in the Garden of Eden (Genesis 3:1-5). How did Satan fall from heaven? Actually, a fall is not an accurate description. It would be far more accurate to say God cast Satan out of heaven (Isaiah 14:15; Ezekiel 28:16-17). Satan did not fall from heaven; rather, Satan was pushed out of heaven.