The problem with envy and jealousy...

... is that they take a dissatisfaction with God and the circumstances that he's placed you in and project them onto a (often innocent) third party.

They turn love to hate. (Genesis 4, 1 Sam 18:6-9)
They distract disciples from following. (John 21:18-22)

Cain's problem wasn't Abel, Saul's problem wasn't David and Peter's problem wasn't John. Their problem was with God, and simply focussed on someone else.

Nasty, nasty stuff that, by the above definition, crouches at the door just when you're most down.

Summary of the 3-part gospel cure:

1. When we're dissatisfied or in trouble, the gospel says come to God directly to lodge your complaint. Let God have it (in both senses), don't take it out on someone else.
2. The gospel teaches us that God owes us nothing, but has given us grace upon grace upon grace. He doesn't owe us, he owns us.
3. The gospel is the message of a pearl more valuable than anything you've ever known. A person you'd sell everything you own in order to know. In a heartbeat and with a smile on your face.
   
   If you know Jesus, you've got the pearl. Why be jealous of someone holding a bag of rubbish? (Philippians 3:7-8)