Grant Richison begins his comments on Philippians 3:7-8, he opens by saying, “In the immediate context we have seen the autobiography of an intensely religious man. Paul has just listed seven 
accomplishments he thought would commend him to God. He supposed he could gain God s favor by his religion.” Then he goes on to explain the next two verses. He says, “Verses seven and eight give Paul s estimate of his scrupulous religiosity in one word—manure.” Paul writes, “But whatever gain I had, I counted as loss for the sake of Christ. Indeed, I count everything as loss because of the surpassing worth of knowing Christ Jesus my Lord. For his sake I have suffered the loss of all things and count them as rubbish, in order that I may gain Christ.”
Paul had all the qualifications of an expert Jewish expert. He was a man who stood head and shoulders above his contemporaries as far as religious knowledge, zeal, and position were concerned. His heritage was pure and his credentials above reproach. But Paul wrestles with a category to put all his many qualities in. Where shall I store these things so that I understand their value? Most English translators euphemize this phrase by using words like “rubbish” or “”garbage.” But the truth is “dung” or “excrement” is the literal meaning of the Greek word. Previously, these things made his life what it was. It gave him status, wealth, respect and much more. He comes up with the word “manure” because now they were worthless to him because everything he needed came through his faith-connection with Jesus. The category he chose to store his accomplishments in was the same category that Isaiah chose for storing his “righteousness.” Isaiah 64:6 says, “When we display our righteous deeds, they are nothing but filthy rags.”
Richison continues his comments, “Paul came from the right nation—Israel, the right race—Hebrews, the right sect—Pharisee; he had the right drive— zealous. He was always up on his sacrifices. He was scrupulously righteous. Yet all that was manure (dung). All these things were weights, not wings. They were the rags of religion, the relics of superstition.” In his commentary, James Boice talks about his days in Switzerland when an epidemic of typhoid broke out in a beautiful little mountain town near the Matterhorn. It took them some time to find the source of the disease. He says, “The water main passing through the town had a crack in it, and the animal refuse from the fields was dripping into the crack and from there into the main water supply. The typhoid bacillus had bred there, contaminating the pipe and the pure mountain water that passed through it.” Like the refuse from the fields our works of righteousness seep into our lives and contaminate us. They do not make us healthy. They make us sick. And as John Piper observes, “It’s true—gloriously true—that none of God’s people, before or after the cross, would be accepted by an immaculately holy God if the perfect righteousness of Christ were not imputed to us.”