Man left to himself will never believe on Jesus. No, they didn't deduce this greatest fact of history on their own. As they listened to and observed Jesus, God opened their hearts to the truth. What a definitive teaching of salvation. God opens the heart.
Men receive the gift of faith and begin to learn.
It comes from the Greek word ekklesia . This could not refer to a particular local church . If this were a particular church, then only that church would receive the promise of the Lord. Also we realize that at this point, they had no concept of a local church like ours. This could not refer to local churches in the institutional sense .