It happened long before Eve took the first bite of the forbidden fruit; God had a Name that He would use to save the world. And yet He kept it a special secret.
Although Job remained faithful through trials, he referred to Him as Redeemer. Although Moses would deliver His people from Egypt, to Moses He was simply the Great I Am. Although David took down a giant and established a kingdom, He most famously called Him Shepherd. Although Isaiah would prophecy of His coming, he could only call Him "Wonderful, Counselor, Mighty God, Everlasting Father, Prince of Peace."
Gabriel had waited so long to reveal the Name. Israel had known countless great heroes: statesmen, warriors, intellectuals, prophets. Even Abraham – whom God called "friend" – had never been able to call Him by name. For thousands of years of human history, Gabriel had waited. But now the day was finally here. At last, God had chosen the first person to hear His Name.