Christ said to the men He had chosen: “As the Father has sent me, I also send you.” (John 20:21)
He commanded them go and preach the doctrines He had taught. He sent them to all nations, promising salvation to those that would believe and threatening condemnation to those who refused to believe. “He who believes and is baptized shall be saved, but he who does not believe shall be condemned” (Mark 16:16). God is just; He would not have threatened condemnation to unbelievers unless He had given the means necessary to believe. His Church is this means; all men must join it.