Till now, with religious affiliation being understood as just another component of a person's identity, we are still in Stage One. We do not encounter Stage Two until we grapple with Paul's own faith journey, recounted in Phil 3:
If someone else thinks they have reasons to put confidence in the flesh, I have more: 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; as for zeal, persecuting the church; as for righteousness based on the law, faultless. But whatever were gains to me I now consider loss for the sake of Christ. What is more, I consider everything a loss because of the surpassing worth of knowing Christ Jesus my Lord, for whose sake I have lost all things. I consider them garbage, that I may gain Christ and be found in him... (Phil 3: 4-9 NIV).
The key term here is "skubelon," translated garbage. This is the only use of the term in the Bible, and its literal meaning is stronger than just rubbish or garbage. The KJV translates it as "dung". It is an incredible statement for Paul to make about his upbringing.
Here we have this apostle, a Pharisee to Pharisees, fully cognizant of his blueblood lineage, and he renounces it all for the sake of sitting down at table with pigeaters! For the sake of Christian brotherhood, he despises his heritage -- and his former allies responded with a vengeance in Jerusalem, attempting to assassinate him ("He has brought Greeks into the Temple area!" (Acts 21:28).
Note that he doesn't totally repudiate his Stage One identification, as is made clear in Romans:
"I have great sorrow and unceasing anguish in my heart. For I could wish that I myself were cursed and cut off from Christ for the sake of my people, those of my own race...My heart’s desire and prayer to God for the Israelites is that they may be saved" (Ro 9:2-3, 10:1).
He loves Israel and believes in its divine calling. However, his identification with other believers in Christ takes precedence over his ethnic upbringing. More than this, it is clear that for him, upholding allegiance to an Old Covenant identity is a sin against the Body of Christ. Accordingly, Paul confronted Peter in Antioch when he separated himself from the Gentiles (Gal 2:11-13).
This same issue is a stumbling block for millions of modern Christians too. Raised up and affirmed in a gender and ethnic/national identity, he or she retains a strong hold on this affiliation alongside a commitment to Christ. At the same time, he or she may make common political cause with fellow Stage-One members against "outside" Christians, ie. Christians who belong to other social or ethnic groups: demanding "respect," "civil rights," "empowerment." Like Peter, these Christians, some of whom are in pastoral or other leadership roles, try to maintain a dual allegiance to Old and New Covenants. They carry over inter-group conflict from Stage One identities into their Stage Two commitment to Christ. This is a sin against the Body of Christ, because it sows discord among believers of other backgrounds.
To count one's own heritage, one's own identity, as "skubelon" is a radical step. It is not a step into the void, it is a step up into Christ. It is a transfer of primary loyalties, of drinking from a new well of self-worth. “Truly I tell you,” said Jesus, “no one who has left home or brothers or sisters or mother or father or children or fields for my sake and for the gospel will fail to receive a hundredfold in the present age—houses and brothers and sisters and mothers and children and fields, along with persecutions" (Mk 10: 29-30). What Jesus is describing is the transition from Stage One to Stage Two, from Old Covenant identity to New Covenant identity. When one embraces the "outsiders" as brother and sister for the sake of Christ, then old friends and family may protest and reject him, even call him "traitor."
Elsewhere, Paul instructs his congregation to "complete my joy by being of the same mind" (Phil 2). This will never happen while church members are divided by loyalties to different races, nationalities, political parties, etc. In his day, and in ours, the precondition to Christian unity is for believers to put their Stage One affiliations on the altar, ie. count them as "skubelon."