YES, you will be going. Praise God, you are judged by CHRIST'S perfect record, NOT your own. If you are a true Christian, washed in the blood of Jesus, you will be going. God has removed our sins as far as the east is from the west. He remembers them no more. Literally, our life record is OVERWRITTEN by the perfect record of Christ's life. He became our sin so that we could become His righteousness (2 Corinthians 5:21).
Someone who is "lukewarm", to me, is one who is undecided. One who hasn't yet made a decision in regards to God. Someone who is cold, easy, they don't go. Someone who is hot, easy, they do go. But the lukewarm... they don't make a commitment either way. God is basically saying choose me or not, don't ride the fence. I would think agnostics fit in this category.
BUT, here's the wonderful thing. Christ's death on the cross absorbed ALL God's wrath for you. ALL OF IT. He will NOT put His blood-bought children through "double jeopardy". We cannot feel the wrath of the Trib because JESUS took that wrath upon Himself.
There is no such thing as a Christian going through the Trib to "purify" them.
We are ALREADY pure in the sight of God, because we are covered by CHRIST'S perfection Spiritually. We will gain that perfection physically at our glorification (Rapture), but the down payment of that future glorification is the Holy Spirit dwelling within you.
Do not fret. You are going. God judges us on Christ's perfection, not on our sinfulness. He remembers our sins no more! \O/ Rest in that freedom. You are FREE.
Whom have I in heaven but You? And there is nothing on earth that I desire besides You. My flesh and my heart may fail, but God is the strength of my heart and my portion forever. ~~Psalm 73:25-26 (ESV)