Dear Diego:

To understand the Bible, we have to understand the context, the Jewish traditions, the conventions of the time, etc.

In Jewish tradition heaven had three levels. We see reference to this when St. Paul said that he was "caught up to the third heaven" in 2 Corinthians 12:2.

The First Heaven is the atmosphere of birds and clouds. The Second Heaven is the realm of the sun and stars. The Third Heaven is the dwelling of God.

We also need to know that in biblical language "stars" often represent angels (Rev. 1:20; 9:1; Judges 5:20; Job 38:7). In Revelations 12:3 the "red dragon", which is Satan, and a third of the stars (angels) were cast out of heaven (imaging falling stars in the sky, the realm of the stars -- the Second Heaven).

Thus, the Scriptures are not saying that the angels were in heaven, the place where God dwells, but is merely making an analogy of falling stars from the sky.

Like Man, angels began is a state of innocence, endowed with supernatural grace, on probation, and tested. Like Man, some of the angels failed the test and fell. Those who fell lost their state of innocence and the supernatural grace, became evil, and were thrown out of the angelic version of the Garden of Eden, sort-to-speak.

The Angels, as well as Man, were created in a state of innocence and with supernatural grace. One third of the angels, and our First Parents, Adam and Eve, fell from innocence  and thus lost that supernatural grace. Man was thus kicked out of the Garden of Eden, and the fallen angels, too, were kicked out of an angelic version of a Garden of Eden, I guess we could say.

Thus, Lucifer and his cohorts, like the all other angels are pure spiritual beings without any body, and in their original state they are endowed with supernatural grace and placed in a condition of probation. It was only by their fall that they became devils. This event is referenced in Revelations 12:7-9; Jude 1:6; 2 Peter 2:4; Job 4:18; Isaiah 14:12-15; Luke 10:18; Ezekiel 28:12-15.

St. Thomas Aquinas suggested that the sin of Lucifer may have consisted in desiring to attain supernatural beatitude by his natural powers, rather than by a gift of God, in a pride of his own powers. But, this is not possible. The beatific vision transcends the natural powers of the intellect and thus cannot be attained except by the express gift of God. 

Another theologian, Scotus, suggested, that the sin of Lucifer was spiritual lust. Still other theologians have suggested that it was the mystery of the Divine Incarnation revealed to them by God that caused Lucifer and the angels to rebel. In this theory it was revealed to the angels that "a nature lower than their own was to be hypostatically united to the Person of God the Son, and that all the hierarchy of heaven must bow in adoration before the majesty of the Incarnate Word; and this, it is supposed, was the occasion of the pride of Lucifer" (Devil, Catholic Encyclopedia).

We really cannot know the details of the Probation of the Angels and exactly why or how they rebelled. We merely know they did. We know they began in a state of innocence and supernatural grace, as did Man. We know that they were on probation and tested, as was Man in the Garden. We know that some angels failed the test, as did Man.

We know that the angels did not hold the beatific vision before they were tested. Once tested those angels who passed the test were immediately enlightened by the beatific vision and entered into the eternal glory of God.

We know that once angels or man enter into the beatific vision, as St. Thomas stated and Fr. Trigilio mentions in his article, it is is no longer possible to be tempted to sin. As Fr. Trigilio concluded, "Ergo, once an Angel or Human Being HAS the Beatific Vision, they are COMPLETELY and TOTALLY and PERFECTLY satisfied."

Lucifer and his cohorts, by their rebellion, were permanently barred from the beatific vision and thus left to implode upon themselves in evil. It is interesting that in English the word "evil" is the backwards of "live". Indeed, Satan and his cohorts are not spiritually alive.

With Man it is the same. We each are on the probation of this life on earth. We each have a choice. If we choose God, then we enter into His beatific vision in heaven. If we choose against God, then we are forever deprived of His friendship and beatific vision.

God Bless,
Bro. Ignatius Mary