Luke 1:16–17 (ESV)

16 And he will turn many of the children of Israel to the Lord their God,

This greatness is also connected to change or repentance as John’s preaching will cause many Israelites to turn back to the Lord their God. In that connection the angel mentions a striking similarity between John and the mighty Old Testament prophet, Elijah. In some ways John will fulfill what the prophet Malachi predicted (Malachi 4:5–6). He will both change and prepare hearts.