He writes in Philippians 3:3-11
3 For it is we who are the circumcision, we who worship by the Spirit of God, who glory in Christ Jesus, and who put no confidence in the flesh-- 4 though I myself have reasons for such confidence. If anyone else thinks he has reasons to put confidence in the flesh, I have more: 5 circumcised on the eighth day, of the people of Israel, of the tribe of Benjamin, a Hebrew of Hebrews; in regard to the law, a Pharisee; 6 as for zeal, persecuting the church; as for legalistic righteousness, faultless.
7 But whatever was to my profit I now consider loss for the sake of Christ. 8 What is more, I consider everything a loss compared to the surpassing greatness of knowing Christ Jesus my Lord, for whose sake I have lost all things. I consider them rubbish, that I may gain Christ 9 and be found in him, not having a righteousness of my own that comes from the law, but that which is through faith in Christ-- the righteousness that comes from God and is by faith. 10 I want to know Christ and the power of his resurrection and the fellowship of sharing in his sufferings, becoming like him in his death, 11 and so, somehow, to attain to the resurrection from the dead.
In this passage, Paul ridicules Christians who have failed to understand life of faith in Jesus Christ.
Christianity is not Jesus plus but Jesus alone. There is no upper class or lower class. There is no Greek and no Jews. All are same.
We are all sinners saved by grace through faith. There is no righteousness or good work except the work of our Lord and Saviour Jesus Christ on the cross which is capable of bringing salvation to human beings.
In fact, all that we consider profit for us from the worldly perspectives are actually loss.
I. Our profits are Loss
For an example, you want to brag about your profit through circumcision, the sign of the Abrahamic covenant.
I was one among them, but that did earn salvation to me.
You want to talk about a lineage as God’s chosen people, I am born as Benjamite. In case you do not know, Israel had its first King Soul from the tribe of Benjamin. You may also like to know that the tribe of Benjamin were the only tribe who did not betray King Solomon and joined the tribe of Judah to form the blessed southern kingdom of Isarel.
But such a lineage do not attain eternal life for me.
I also would like you to know that I am son of Pharisee trained as Pharisee under the great teacher Gamaliel. I was well informed on legal aspect of the rule and I have observed the rule legalistically.
However, these credentials did not earn salvation for me.
I was passionate devotee of the God of Israel. I was on a mission to destroy all Christians from the face of the earth because I saw them as heretics. I was one among those who encouraged the public killing of Stephen. However, all militant zeal of YHWH did not bring salvation to me.
No! none of these credentials helped me to attain salvation.
In fact, if I bank on these credentials, and try to make profit out of it. It will make proud and arrogant and unfit for the salvation.