It is good for Christians to define their terms biblically so to better realize all we have in Christ. Eph. 4.4-6: There is one body and one Spirit, just as you too were called to the one hope of your calling, one Lord, one faith, one baptism, one God and Father of all, who is over all and through all and in all. Here, Paul lists the first singularity of the faith: “one body.” This is what some have called “the universal church.” I prefer the term: “the one body,” however, and seek to trace it in the New Testament to arrive at a definition.
In the context of the Ephesian letter, Paul urges many commands and practical applications to the believers that will glorify God and give the proper picture of Christ’s followers to the world. To help with a definition and to see the nature of the church clearly, however, I will use two sections from the gospels:
Mt.16.16-18: Simon Peter answered, “You are the Christ, the Son of the living God.” And Jesus answered him, “You are blessed, Simon son of Jonah, because flesh and blood did not reveal this to you, but my Father in heaven! And I tell you that you are Peter, and on this rock I will build my church, and the gates of Hades will not overpower it.
Jn.7.6: I have revealed your name to the men you gave me out of the world. They belonged to you, and you gave them to me, and they have obeyed your word.
The Greek word used in our bibles for “church” is “eklesia,” a compound word using the verb “call” (kaleo) and the preposition “out” (ek). It refers to people assembled out from their ordinary places. So we see the John reference (7.6), which is the section that Christ prays to The Father for His disciples and future believers, a definition: “the men you gave me out of the world.” This is the original 11 true disciples. So it may be said that Christ prays for His church here. An element to notice is that The Father gave them (the original disciples and future believers) to Jesus. This agrees well with the Matthew passage which states that it was The Father who revealed the true personhood of Christ to the disciples. This is “the rock” upon which Christ builds “the church,” the one body He prays for in John 17.
Please read Mt.16, Jn.17, and Eph.4 for all the rights, privileges, protections, and obligations we have by being united with Christ.