Luke 1:77 To give knowledge of salvation unto his people by the remission of their sins.
Zechariah continues his prophecy about his baby boy, John: He will be called the prophet of the Highest, and he will go before the Lord to prepare his ways. Then he gives this prophecy: he will prepare the way for the Lord to come by repentance and baptism for the remission of their sins. This John did. And this is the promise: he will give his people knowledge of salvation.
We have been promised the knowledge of salvation. Jesus is salvation. He is the Savior. We know Jesus by faith, after hearing the gospel of grace. God promises knowledge: we “know” Jesus. We know who He is and what He did. We know the salvation He is and the salvation He gives. We do not just hope, wish, dream, or just want it to be so. We know. We know what He saved us from; we know what He saved us for.
Faith is a personal relationship with Salvation and with the One Who Saves. We live in a different world; we live in the world of salvation; we live the life of the age to come. Indeed, we still live in this sin-cursed world that we can see, but at the same time we live in the sin-free spiritual kingdom that we can’t see. We know this world. We live in this world. And we live from this world, for we have the knowledge of salvation by the forgiveness of sins.