As far back as 1837, the General Assembly declared that the church, by its very nature, is a missionary society whose purpose is to share the love of God in Jesus Christ in word and deed and with the entire world. Witnessing to the good news of Jesus Christ throughout the world, Presbyterians engage in mission activities, seek to alleviate hunger, foster self-development, respond to disasters, support mission works, preach the gospel, heal the sick, and educate new generations for the future. In partnership with more than 150 churches and Christian organizations around the world, the missionary efforts of the Presbyterian Church (U.S.A.) involve approximately 1,000 volunteers and compensated personnel.

Some of the principles articulated by John Calvin remain at the core of Presbyterian beliefs. Among these are the sovereignty of God, the authority of the scripture, justification by grace through faith, and the priesthood of all believers. What they mean is that God is the supreme authority throughout the universe. Our knowledge of God and God's purpose for humanity comes from the Bible, particularly what is revealed in the New Testament through the life of Jesus Christ. Our salvation (justification) through Jesus is God's generous gift to us and not the result of our own accomplishments. It is everyone's job - ministers and lay people alike - to share this Good News with the whole world. That is also why the Presbyterian Church is governed at all levels by a combination of clergy and laity, men and women alike.