1:3 infallible proofs. “Infallible proofs” is one word in the Greek (tekmerion) and occurs only this one time in the New Testament. It emphasizes that the evidences for Christ’s resurrection were not philosophical speculations but certain facts! It is appropriate that the word occurs only once, for no other event of Biblical history has been confirmed more certainly than His bodily resurrection. Not only His ten or more appearances to the disciples, but also the otherwise inexplicable evidence of the empty tomb, the remarkable change in the disciples, the development and spread of the church as a result of its preaching, the change to worship on the first day of the week, the age-long observance of Easter and the Lord’s supper, all in addition to the testimonies of the writers of the New Testament, as led and empowered by the Holy Spirit. These all combine to make it certain that Christ died for our sins and rose again for our justification.

1:3 forty days. As Jesus was victorious over His forty-day temptation by Satan (Luke 4:2), so He witnessed to His disciples for forty days of His greater victory over Satan through His death and resurrection (Hebrews 2:14-15).