It does not come from being a physical descendant of Abraham. The Apostle Paul taught likewise. The true Jew was not one outwardly through the circumcision of the flesh. The true communion of the Church was something inward, a circumcision of the heart, a heart awakened by God to a living spiritual life that put off the ways of the flesh - a heart that clung tenaciously to the righteousness of His Son, Jesus Christ. This is the only real community of heaven.
Community does wonderful things.
It binds and blesses with the force of faith and love. Love binds us to men, enabling us to know each other, to forebear each other's weaknesses, sins and failings so that we do not fragment into a thousand islands of rivalries and individualities. Wrong bonds make for weak bonds. Weak bonds make for fragmentation. Fragmentation creates desperation.