Last weekend I read the book "The Prodigal God" by Tim Keller. The book is about the parable of the lost son. I really, really liked it! It revolutionized my understanding of this parable and touched into some deep places of my heart. Most of the times I have heard this parable taught, the majority of the attention is placed on the wayward son to show us all about God's great forgiveness. Second to the young son, the Father would be most popular for welcoming the son back home after his great dishonoring adventure.
Not so with the perspective of this book. Keller says this story is mainly about the older son and the damaging heart disease of the older son. And its is exactly the "older sons" that Jesus was addressing when he told this story. Read Luke 15:1.
Here's the problem with the eldest son: He was not aware that he was doing anything wrong, so naturally, he had no need for returning to the Father in repentance. "Older Brothers" are impressed with all they do right, full of pride and unaware of the rejection and pain they cause the Father. Older brother syndrome is a deeply dangerous condition. And, if you have been serving the Lord for a long time, it might be possible that you are infected with it.
I highly recommend this book to you.