Christ bestowed unity on his Church from the beginning. This unity, we believe, subsists in the Catholic Church as something she can never lose, and we hope that it will continue to increase until the end of time. Christ always gives his Church the gift of unity, but the Church must always pray and work to maintain, reinforce, and perfect the unity that Christ wills for her. The desire to recover the unity of all Christians is a gift of Christ and a call of the Holy Spirit.
Human service is the idiomatic phrase.
822 Concern for achieving unity involves the whole Church, faithful and clergy alike. But we must realize that this holy objectivethe reconciliation of all Christians in the unity of the one and on Church of Christtranscends human powers and gifts. That is why we place all our hope in the prayer of Christ for the Church, in the love of the Father for us, and in the power of the Holy Spirit.