You teach that the reference to Lucifer in Isaiah 14:12 is speaking of Satan, but the word "Lucifer" is the latin word for "morning star." 2 Peter calls Jesus the Morning Star, so isn't Isaiah 14 talking about Jesus and not Satan?
While it is true that the word "lucifer" means "morning star" in Latin, this does not mean that every mention of a morning star in Scripture is a reference to Christ. Remember, Scripture tells us that Satan comes as an "angel of light," and therefore at times he passes himself off as the Morning Star, that is Christ. Scripture acknowledges this pattern by assigning Satan the messianic term "morning star" in a mocking manner.
Because the phrase "morning star" (or lucifer) is used both as a description of Christ and of Satan, we must rely on the context of each use to help us determine the meaning. The rules for proper interpretation of scripture require that the context drive our understanding of the meaning of a single word; a single word doesn not drive our understanding of the context.
In Isaiah 14:12, we read:
Is. 14:12 “How you have fallen from heaven,
O star of the morning, son of the dawn!
You have been cut down to the earth,
You who have weakened the nations!
In the Latin Vulgate translation, the word for "star of the morning" in Isaiah 14:12 is the word "lucifer." Who is Isaiah describing in v.12? To answer that question, we must consider the entire context of Isaiah 14. As we look at that chapter, we find abundant evidence that the entire chapter is describing Satan's fall.
For example, Isaiah 14 also calls this individual the "king of Babylon" (v.4), which is a reference to Satan and never Christ. Furthermore, this person is welcomed into Sheol to lie on a bed of maggots (v.11), which is not something prepared for Christ. Also, in v.14 Lucifer is accused of weakening the nations (not something Christ did), and in v.20 he is accused of slaying his people (not something Christ did). Simply put, it is impossible to conclude from the context of Isaiah 14 that Lucifer is a reference to Christ. We must conclude it refers to Satan.
In summary, we must guide our understanding of the word lucifer by the context in which it appears. In Isaiah 14, the context clearly shows this word used to describe Satan. On the othe hand, 2 Peter is clearly using the term to describe Christ, as you pointed out. There is nothing surprising nor troubling about the Bible using the same word to refer to two different people or concepts.
