Let’s consider three things in answering this excellent question:

  1. Heaven was a perfect place but Lucifer was still capable of sinning. We read of his sin in Isaiah 14:12-14: “How you are fallen from heaven, O Lucifer, son of the morning…For you have said in your heart: ‘I will ascend into heaven, I will exalt my throne above the stars of God…I will ascend above the heights of the clouds, I will be like the Most High’” (NKJV). In Ezekiel 28:12 & 17 we learn what caused him to sin: “You were the seal of perfection, Full of wisdom and perfect in beauty…Your heart was lifted up because of your beauty; You corrupted your wisdom for the sake of your splendor.” These passages teach us that Lucifer’s heart was lifted up with PRIDE and this caused him to rebel against God. The fact that heaven was a perfect place did not prevent Lucifer from sinning. We can relate this to the Garden of Eden and the fall of Adam, for Eden was also a perfect place yet Adam sinned. Both Lucifer and Adam were created in perfection, but NOT “sinless perfection.” By that I mean they were not “holy,” for had they been created in absolute holiness they would not have been capable of sinning. God chose to create Lucifer and Adam with a free will which gave them the choice to worship and follow their Creator, or to rebel against Him.
  2. Heaven became defiled by Lucifer’s sin. We read in Job 15:15, “God puts no trust in His saints, and the heavens are not pure in His sight.” The heavens were surely “pure in His sight” BEFORE Lucifer’s rebellion, but once he sinned the heavens were defiled. Another passage that bears this out is Hebrews 9:22-23, “And according to the law almost all things are purified with blood, and without the shedding of blood there is no remission. Therefore it was necessary that the copies of the things in the heavens should be purified with these, but THE HEAVENLY THINGS THEMSELVES WITH BETTER SACRIFICES THAN THESE.” Israel’s earthly temple was a “copy” or “picture” of heaven, and here we learn that just as the temple needed to be purified with the blood of an animal sacrifice, so heaven itself needed to purified with a better sacrifice. That sacrifice was the Lord Jesus Christ and the blood that He shed on the cross.
  3. Heaven will one day be free from defilement forever. 2nd Peter 3:12-13 declare: “Looking for and hastening the coming of the day of God, because of which the heavens will be dissolved…nevertheless we, according to His promise, look for NEW HEAVENS and a new earth IN WHICH RIGHTEOUSNESS DWELLS.” These verses speak of the eternal state when God will create “new heavens and a new earth.” The phrase “in which righteousness dwells” means that they will be in a “fixed state of holiness.” Sin will never break out again, for all sinners will be confined eternally to the lake of fire and those in heaven will be perfectly holy and incapable of sinning. Then, and only then, will heaven be a perfect place where there is no sin or the possibility of sin being committed. (239.1) (DO)