The hearers will pass on what they have heard. This is made effective by the accompanying testimony of God himself, who adds his proof. With this he demonstrates the new life, robs unbelief of its arguments, and gives a firm foundation to faith. This witnessing (a legal term!) legitimizes and guarantees the salvation that has been proclaimed.1
4 while God also bore witness by signs and wonders and various miracles and by gifts of the Holy Spirit distributed according to his will.