The church was founded in Genesis 3.
I believe the church is synonymous with Israel in a New Testament redemptive-historical sense because there was a church in the Old Testament. For example, Hebrews speaks of the church in the wilderness.
In its New Testament form, the church began at Pentecost. It emerged slowly, growing from infancy to adolescence, as it experimented with holding all things in common. However, the church stopped this practice when it saw the need for diaconal ministry in Acts 6. Regardless of whether the men in this chapter were strictly deacons, they were certainly diaconal in their ministry. From there, it developed into the full-blown, mature church of the pastoral epistles.