"You are no longer strangers and sojourners"

... but you are fellow citizens with the holy ones
and members of the household of God
built upon the foundation of the Apostle

- Eph 2:19-22

The Church is apostolic because she is founded on the apostles, in three ways:

- she was and remains built on "the foundation of the Apostles," the witnesses chosen and sent on mission by Christ himself;
- with the help of the Spirit dwelling in her, the Church keeps and hands on the teaching, the "good deposit," the salutary words she has heard from the apostles;
- she continues to be taught, sanctified, and guided by the apostles until Christ's return, through their successors in pastoral office: the college of bishops, "assisted by priests, in union with the successor of Peter, the Church's supreme pastor":

You are the eternal Shepherd
who never leaves his flock untended.
Through the apostles
you watch over us and protect us always.
You made them shepherds of the flock
to share in the work of your Son. . . .

- CCC 857