In this section of Philippians, Paul offers his own life experience as a personal example to the Philippians. First, in verses 4-6, he describes his life as Saul. He was a "Hebrew of the Hebrews". He was the ultimate specimen of law-keeping, of zeal, and proper heritage.
However, in verses 7 and 8, he states that all those things are as nothing compared to knowing Christ. Actually, he states that they are worse than nothing, as dung, in comparison.
The application of this can be made to our own lives. Like Paul, we may be thinking we are "doing the best we can". Like Paul, our best is not good enough to be made right with a holy God who can only be satisfied with perfection.
So why was Paul so enamored of Jesus? Why did gaining Christ make all his astonishing previous experience so repugnant to him? Three components of the answer can be found in the following verses.
First, in verse 9, Paul describes how he has received righteousness. He could not achieve righteousness through obedience of the Law, as hard as he tried. But Christ's righteousness - a righteousness from perfect obedience and submission to the Father - is imputed to those who have faith in Christ. This is justification, by grace through faith.
Secondly, in verse 10, Paul describes the great value of knowing Christ. For him and for us, knowing Christ involves much more than just mental assent. It includes a mental understanding and an application of that knowledge to our lives. And it includes an intimate personal relationship, a union with the thing that is known. This is sanctification, a growing understanding of God affecting our lives.
Paul had "resurrection power" (v.10) of the Holy Spirit empowering Him to live this new life. He experienced the fellowship of Christ's sufferings. This isn't referring to some means of earning favor with God through physical affliction. Rather, by experiencing sufferings (mental or physical), we can obtain a deeper understanding of Christ. It is a way He can only be known by those who follow Him.
Verse 10 mentions that Paul wished to be conformed to Christ's death. This is to be understood in a spiritual sense, rather than a physical one. We are conformed to Christ's death when we die to our own selves, our own ambitions and desires, and take on the trust in God that Christ displayed. His death was an utter emptying of Himself, a life of complete self-giving love.
Thirdly, Paul looks forward to His resurrection from the dead. He is saying that in whatever path God has ordained for his life, he will follow Christ, living with Him, dying with Him, and following Him to live in eternal glory. This is glorification.
Paul concludes in verse 12 by acknowledging that he is not perfect (although positionally he is perfect in Christ). His imputed righteousness is perfect, but his imparted righteousness is still being worked out. And Paul commits himself to pressing on vigorously. This is always the pattern; here, as we have seen previously, salvation is all of God, yet our proper response is to follow after him with all of our ability. We do not know all the specific purposes and services for which Christ has "laid hold" on us for this life. All we can do is follow after, like Paul. Then we can "lay hold" on the purposes He has for us in this life. We do know the ultimate purpose of Christ's laying hold on us, and that is so that we may be with him in glory. What a great calling!