WHO IS A DEACON?
A deacon is an ordained minister of the Catholic Church. Deacons are ordained as a sacramental sign to the Church and to the world of Christ, who came "to serve and not to be served.” The entire Church is called by Christ to serve, and the deacon, in virtue of his sacramental ordination and through his various ministries, is to be a servant in a servant-Church.
All ordained ministers in the Church are called to functions of Word, Sacrament, and Charity, but bishops, priests and deacons exercise these functions in various ways. As ministers of the Word, deacons proclaim the Gospel, preach, and teach in the name of the Church. As ministers of Sacrament, deacons baptize, lead the faithful in prayer, witness marriages, and conduct wake and funeral services. As ministers of Charity, deacons lead in identifying the needs of others, then marshaling the Church's resources to meet those needs. Deacons are also dedicated to eliminating the injustices or inequities that cause such needs.
In the middle ages, the Church ceased ordaining permanent deacons and made the diaconate a transitional order before being ordained a priest. However, a group of priests who had been imprisoned in a Nazi concentration camp in the late 1940s were convinced that there was a need to revive the permanent diaconate as it was originally envisioned. This was the role of bringing the gospel and ministry of service into prisons, hospitals, and to the marginalized members of society. They petitioned the Pope to restore this ordained ministry. Pope Paul VI formally implemented the renewal of the permanent diaconate following the closing of the Second Vatican Council.
The deacon leads the community to reflect on their communion and mission in Jesus Christ, impelling the community to live lives of service. Because the deacon sacramentalizes service, he should proclaim the word in such a way that he first witnesses its empowerment in his own life. Then he can effectively challenge others to practice the Church’s ministry of charity and justice. By his own faithful practice of the spiritual and corporal works of mercy, the deacon “by word and example…should work so that all the faithful, in imitation of Christ, may place themselves at the constant service of their brothers and sisters.”
Adapted from USCCB FAQ about Deacons and National Directory for Permanent Deacons in the United States