Lucifer

Lucifer is a translation of the Latin words lucem ferre (from lux "light" and ferre "carry") meaning the "light-bearer". It was the name given to the morning star, i.e., the planet Venus when seen at dawn.

In Cristianity this name is usually associated to Satan. The only time the name "Lucifer" appears in the old testament is in Isaiah xiv:12, where he calls the King of Babylon "Helel" (הֵילֵל, "Shining One"), a Hebrew word that refers to the Day Star or Morning Star (the Latin term for which is lucifer). The verse was interpreted as a reference to Satan in early Christianity. H. P. Blavatsky claimed Pope Gregory I was the responsible for this:

It was Gregory the Great who was the first to apply this passage of Isaiah, 'How art thou fallen from Heaven, Lucifer, son of the morning,' etc., to Satan, and ever since the bold metaphor of the prophet, which referred, after all, but to an Assyrian king inimical to the Israelites, has been applied to the Devil.

In the book of Revelation (2:28) Jesus says he will give "the morning star" to "the one who is victorious and does my will". In his Notes on the New Testament, Albert Barnes comments:

The "morning star" is that bright planet--Venus--which at some seasons of the year appears so beautifully in the east, leading on the morning--the harbinger of the day. It is one of the most beautiful objects in nature, and is susceptible of a great variety of uses for illustration. It appears as the darkness passes away; it is an indication that the morning comes; it is intermingled with the first rays of the light of the sun; it seems to be a herald to announce the coming of that glorious luminary; it is a pledge of the faithfulness of God.

For this reason Mme. Blavatsky wrote:

So absurd and ridiculous is that prejudice, indeed, that no one has seemed to ever ask himself the question, how came Satan to be called a light-bringer.

Further reading

• Lucifer at Theosopedia