When Christ was on the earth he established a church. It was called after His name and built on His doctrine. He called twelve apostles (Matt. 10) to help govern the church. As the church grew, Christ called "other seventy also, and sent them two and two before his face" to declare Christ's message abroad (Luke 10:1). After Christ's death, the twelve apostles were left to govern the affairs of the church in the savior's stead. The group of twelve apostles was meant to continue on as illustrated in the first chapter of the book of Acts. Matthias is called to fill the vacancy left by the traitorous Judas Iscariot. Somewhere along the line, the priesthood; held by the apostles; was lost. The church over which they governed was corrupted and distorted. Over hundreds and even thousands of years, many Christian churches were established and spread around the world.
In our present day, Christ has established His church to the earth. He has restored the priesthood through John the Baptist and three of His original apostles. He has restored the keys of baptism and the apostleship. The church of Jesus Christ is on the earth.
One remarkable thing I've noticed of Christ's restored church is that it's the same wherever you go. I grew up in Pennsylvania and attended church my whole life. When I went away to school and attended church there, I was amazed that it was very much the same church. On my mission I've attended church in Montana and Wyoming and guess what, it's the same church. Vastly different people gathering to worship in tremendously varied locales around the world are all unified in their love for, their testimony of, and their devotion to the Lord Jesus Christ. His Kingdom is on the earth. It will continue to fill the world. And the doctrines will be kept pure through the leadership and church government established by Him from whom it came.