The church that Jesus established was one world wide church. Jesus said, "Go into ALL THE WORLD and preach the gospel to ALL CREATION" (Mark 16:16).
This was accomplished by the first generation of Christians (Colossians 1:5-6,23). Why not also by our generation?
In the first century, wherever the church was established, it was one and the same kind of church. There was only one kind of church in each place; so although there were many congregations world-wide, they were one body, with one Lord, one faith, one baptism (Ephesians 4:3-6).
They were all "the churches of Christ" (Romans 16:16). "All in every place" were of one name and one Lord (1Corinthians 1:2).
When Paul writes to "the churches of Galatia" (Galatians 1:2), he is not thinking of denominations, each following different faiths.
When Paul was travelling "through Syria and Cilicia, strengthening the churches" (Acts 15:41), he was not visiting different fellowships following different creeds.
When John wrote to "the seven churches of Asia" (Revelation 1:4), they were churches of the same origin and kind. Heresy and malpractice in some of these churches was condemned by Jesus who told them to repent of these departures from the norm (Revelation ch 2,3,4).
there was one kind of church the world over, following one rule of faith, wherever the church was found. Christ prayed for this unity and order (John 17:11)
The church worldwide had only one law or rule of faith. This rule consisted of the teachings of Christ (Matthew 28:18-20), of the Holy Spirit (John 14:26), and of the apostles (Acts 2:42).
Nothing but this gospel was acceptable as the revelation of truth (Romans 1:16-17, Gal 1:6-9). The church was built on the foundation of this preaching (Ephesians 2:17-22).
The teachings were written as well as spoken, and these writings were for the complete instruction of the church (2Timothy 3:16-17).
Notice what the church was to do with this instruction:
(1) Pay close attention to it (Hebrews 1:2, 2:1-4),
(2) Abide in it (1John 2:3,24; 2John 1:9),
(3) Earnestly contend for it (Jude 1:3).
"Endeavour to keep the unity of the Spirit in the bond of peace —one body and one Spirit just as you were called in one hope of your calling, one Lord, one faith, one baptism, one God and Father of all, who is above all, and through all, and in you all" (Ephesians 4:3-6).