Which cuts through a bunch of the smoke and fog on the matter. I would add besides Judah's and Simon's understanding of the word Demostones' and Hercules', two Greek converts or Julius and Cicero, two Roman (native Latin speaker) converts.
I think that Martin though was spot on on this issue! I think that it is mainly Landmark Baptists who balk at any suggesting that there is a Universal church in the Bible supported!
The Spirit empowered the already existing church on the day of Pentecost. The word "ekklesia" means "called out assembly." Jesus "called out" his disciples to follow him during his ministry, NOT after. His church began the moment the first disciple began to follow Him.
1. Notice, in Matthew 18:17 Jesus tells his disciples that if they have a quarrel, they should tell it to the "church." The church already existed during that time.
2. In Matthew 16:18 Jesus said that "upon this rock, I will build my church." The words "will build" can be translated as "I will continue to build" meaning the church was already in existence.
3. Notice how in Acts 2:41 three thousand that were saved were "added." How can they be added to something that does not exist yet. The church already existed and had at least 120 according to Acts 1:15.
4. In Acts 1, a new Apostle was selected to replace Judas. Who had the authority to select them in here? The already in existence "church." Notice how in 1 Corinthians 12:28 it says, "And God has placed in the church first of all apostles." How can there be apostle first before the church existed? It cant happen. The church existed first, then Jesus chose among his church the 12 apostle in Luke 6:12.
If we want to be more specific, the church started in John 1:35-39 when He "called" Andrew and Peter to a life commitment of discipleship. That's when He "ekklessia" them and the N.T local church began!
I am a firm believer that Christ's church was started by Christ during his earthly ministry.
But I would not use Matthew 16:18 as a proof text. The word translated "I will build" is οικοδομησω and is a future tense, active, indicative verb.
It does not mean that the called out ones were not already assembling with Him, but rather indicates in the future He will build up His assembly. As he did on the day of Pentecost, and following.
That verse does not support your position in the way you suggest. :)
I take the Matthew passage as marking the conception of the church. While I take Pentecost to be the day the church was born. IOW, from Matthew to Pentecost the church existed in embryonic and fetal states.