The Church is not a building. No, in the New Testament, written in Koine Greek, our English translations of it where we find the the word “church,” it is a translation of a form of ἐκκλησία (ekklēsia)….
For example, in Acts 5:11, “καὶ ἐγένετο φόβος μέγας ἐφʼ ὅλην τὴν ἐκκλησίαν καὶ ἐπὶ πάντας τοὺς ἀκούοντας ταῦτα,” which the NASB translates as, “And great fear came over the whole church, and over all who heard of these things,” contains ἐκκλησίαν (ekklēsian), which is the accusative, singular, feminine case of ἐκκλησία. All that means is that ἐκκλησίαν is the direct object of the main verb in that sentence. However notice that there is just one ἐκκλησία. “This word literally means, “the called out ones.” It’s usage in scripture denotes the New Testament community of the redeemed in a two-fold aspect, the first referring to all those called by and to Christ in the fellowship of His salvation, which is the “Church” worldwide at all times. The second aspect, rarely used, refers to a local body of believers.
In our Lord’s prayer in John 17, we read Him praying for unity amongst and holiness for His people. He prays for their sanctification and that they love one another. It won’t take long in our day to see that there is much division in the visible Church. There is a great deal of conflict and there is little personal holiness evident as well. The focus of most professing Christians is on themselves. Does this mean that our Lord’s prayer for His Church was for naught?