My goodness, guys. Christians arguing about the most basic of Christian tenants? This is wrong. If you call yourself a Christian, your faith must be informed by God's Word (taken in context, not out of context).
Lucifer isn't a representation of anything. He was the greatest worship leader of angels in Heaven. He wanted to take God's throne and be God. Naturally, God was peeved and threw Lucifer and his angels out of Heaven. Lucifer is now known as Satan. He is bad news, very bad news. But he's not a symbol, he's very real.
Christ became sin for us. That doesn't mean he was a sinner. It means he was nailed to the cross with all of humanity's past, present and future sins upon him. In the Father's eyes he took on all of our sin and faced God's Wrath, died and then rose again to new life. He faced God's Wrath at sin, so we wouldn't have to, if we just accepted his bloody, atoning sacrifice.
As for the validity of Jesus being God? Of course he's one and the same! You only have to read the Bible to realise that. Not three gods, but one God in three persons - Father, Son, Spirit. The Father governs the Son and the Son governs the Spirit but all live in perfect relationship with each other. The Trinity is never mentioned by name in the Bible but God's Word definitely talks about the three-person hood of God. The Truine God is very much a biblical concept.
I really wonder about some of you and how you study the Bible. You need to read verses in context with the chapters, with the books and with the historical times in which they were written. You need to know the audiences being addressed and the situations/events taking place at the time. Context is key.
Speak God's Truth with love.