When Jesus established The New Covenant, HE identified it as His body of believers, hence the term ekklesia was used to focus upon ALL those who believe/faithe that Jesus is The Savior, their individual Savior. Jesus did not establish and organization and His Holy Spirit does not oversee any particular org, rather The Holy Spirit is individually raising up a bunch of newborns int he way that they should go. By God's Grace indulging use without chastising instantly, there are many, many different additions to the simple Gospel of Grace in Christ, thought up by men (and a few women) forming orgs, the largest and most prominent being the catholic org.
Some of the additions are outright blasphemies, not the authority of The Holy Spirit working in the Ekklesia.