What does Luke 1:68 mean?

Zechariah is celebrating the birth of his son (Luke 1:57). This child will be a powerful herald of the Messiah (Luke 1:13–17; Isaiah 40:3; Malachi 3:1; 4:5–6). His song of praise includes many allusions to the Old Testament. This is not surprising, as Zechariah is a priest (Luke 1:5).

The phrase "blessed be the Lord God of Israel" is seen in several psalms (Psalm 41:13; 72:18; 106:48) and in multiple Old Testament Scriptures (1 Samuel 25:32; 1 Kings 8:15; 1 Chronicles 16:36). This identifies God as the same One who spoke with patriarchs like Abraham (Genesis 12:1–2) and Isaac (Genesis 26:3–4), as well as Jacob (Genesis 28:13), who would later be named Israel (Genesis 35:10).

Another use of the "blessed" phrase is in 1 Kings 1:48. There, David rejoices to know that God has placed his successor on the throne. This is especially relevant to Zechariah's song; his son (Luke 3:2–3) will be a precursor to Jesus Christ (Luke 1:31–33), who will fulfill Messianic prophecy as a descendant of David (2 Samuel 7:12–16; Isaiah 9:6–7).

The concept of Israel being "visited" by God refers to His meeting their needs. This echoes how Israel reacted when they first heard God was going to free them from Egypt (Exodus 4:31). That praise, as well as Zechariah's, reflects a unique way Scripture would refer to God's promises. Though Messiah had not yet come, when Zechariah spoke, God's promises are "as good as done." Referring to what God was about to do as if it was done is seen in other passages of the Bible (Joshua 2:24; Psalm 9:5–8).

Isaiah 43:1 combines several of these concepts, including God's role as Israel's "Redeemer."