Hey! I'm Doing Great!

The last church on earth is called Laodicea. (Revelation 3:14) This is what God says about the condition of Christianity right before Jesus returns.

"To the angel of the church in Laodicea write: The Amen, the faithful and true Witness, the Beginning of the creation of God, says this:
'I know your deeds, that you are neither cold nor hot; I wish that you were cold or hot.
'So because you are lukewarm, and neither hot nor cold, I will spit you out of My mouth.

For you say, I am rich, I have prospered, and I need nothing, not realizing that you are wretched, pitiable, poor, blind, and naked.

I advise you to buy from Me gold refined by fire so that you may become rich, and white garments so that you may clothe yourself, and that the shame of your nakedness will not be revealed; and eye salve to anoint your eyes so that you may see.
Those whom I love, I reprove and discipline; therefore be zealous and repent."  Revelation 3:14-19

God tells us the majority of Christians at the end of time will be relying on themselves. They see themselves as prospering; they see nothing wrong in what they do or say. They think they are doing a great job being a Christian. They are quick to condemn others and never themselves. But God says these Christians are filthy and need to be clothed with Jesus' righteousness - without which no one can be saved. They need eye salve to see their true condition.

If you think you are righteous, why would you feel a need for Jesus? An example of this would be the parable of the Levite and the tax collector who prayed in the temple. One of them listed all his virtues to God. The other said, "God, be merciful to me, a sinner."  Jesus said the second man went home justified.

Laodicia is like ancient Israel who said,

 "Surely I have become rich, I have found wealth for myself; In all my labors they will find in me No iniquity, which would be sin." Hosea 12:7 

But how did they become rich? God said,  "A merchant, in whose hands are false balances, He loves to oppress."
"And now they sin more and more, and make for themselves metal images, idols skillfully made of their silver, all of them the work of craftsmen. It is said of them, “Those who offer human sacrifice kiss calves!” Hosea 13:2 

Finally, in their wickedness, they gave human (child and adult) sacrifice to the god, Baal. Yet they say they have no iniquity!

Why does God warn us? Why does God want us to repent? Is he just being cranky?

No. Because he knows what sin does to other people. He knows sin leads to sadness, suffering and eternal loss. He wants us to repent because of love, love for the entire human race.