Properly understood, the Christian world is one of extreme hierarchy, albeit in an unusual way. Christ, God Himself, comes to Earth and model complete obedience to His Father. The Good Shepherd, willing to lay down His life for the sheep, is also the Paschal Lamb of God.
All of us, likewise, are called to be shepherds as well as sheep. Jesus calls us to the kind of obedience He demonstrates, but also sends us on a mission to gather lost sheep, just as He was sent into the world: “Amen, Amen, I say to you, whoever receives the one I send receives Me, and whoever receives Me receives the One who sent Me.” (John 13:20). Yet as Jesus demonstrated in that same chapter (John 13:1-17), this power is a power to serve. After washing the disciples’ feet, He declares, “I have given you a model to follow, so that as I have done for you, you should also do.” (John 13:15).
And so we see, in a circle outward, that Jesus is sent by God the Father, and in turn sends out disciples/Apostles, who send out Bishops and deacons and elders (or priests, as they soon came to be known) who send laity into the world to convert (ed. the term “Mass” comes from the Latin term for the dismissal, emphasizing the going-out from the Mass; the Mass is a form of spiritual empowerment to enable you to handle your day/week/neighbor).
All of this is somewhat surprising for a God who calls Himself “jealous.” But it makes sense – God is jealous of Baal, not Moses; of Mammon, not Peter. God’s jealous is of anything which draws us away from Him. In contrast, this expanding circle is fueled by God in every step. And it is clear that such a human-run, Divinely-protected Church was His intention: God the Son gathered twelve men when He needed none, and never bothered to write a Holy Book. The Christian message, perhaps more than any other, has been based in large part on the transmission of witness testimony throughout the ages.
In the role of shepherd, Catholic thought uses a surprising term: alter Christus, or “another Christ.” To anyone unfamiliar with the fullness of the Faith, this is shocking and sounds blasphemous and polytheistic. In fact, it is a furtherance of the idea expressed above. Jesus said, “call no man on Earth your Father,” (Matt. 23: 19), yet St. Paul says, “I became your father through the Gospel” (1 Cor. 4:15). St. Paul warns earlier in that epistle, though, that there is no Paul or Apollos, only Christ (1 Cor. 1:12-13). And this is the key that ties it all together.
Christ warns us not to call any man our father so as not to create an alternative to God, a figure to draw us away from God. If we are a Christian but also a Marxist, we find Marx and Christ pulling us in different directions. But to be a follower of St. Paul is to be a follower of Christ. Paul’s fatherhood draws you in to the One Divine Father.
In this way, St. Paul becomes a co-redeemer of sorts: the person who converts to Christianity because of Paul’s preaching of Christ’s message can rightly thank both Paul and Christ for saving him – had Paul resisted the Holy Spirit, the man may have been lost. But in this, he is really thanking Paul only for serving as an alter Christus, as Jesus sent him to be.
What Catholics often call alter Christus, St. Paul describes perhaps more clearly: “With Christ, I am nailed to the Cross; but I live, yet no longer I, but Christ liveth in me.” (Gal 2:20).