NOTES for Mal 3:1-2
In antiquity, in the time of the First, and maybe even of the Second Temple, there was in Israel a feast called "the day of the Lord". Probably, it was held in autumn, somewhere near the Jewish New Year and the feast of Yom Kippur, which in ancient times, and in our days is for the Jewish believers the day of Judgment and repentance.
And in the antiquity the day of the Lord was still as the day of the enthronement of the Lord, with which was connected the experience of the visions of the Throne of glory, of which the tradition with its roots leaves, probably, in deep antiquity, in the time of Salomon. And of course, this day, the day of the celebration of their God, the believers waited it as the day of their personal celebration, the day, when they will see together with their God the gentile world lying at their feet. And God will judge this world, which was formerly often hostile to His people.
The prophet sees the situation completely differently. He says: God will come when we do not expect Him; are you sure that His coming, His feast will be a feast for you too? Repeating in somehow what formerly, before even the captivity said Amos, Malachi reminds to those who listen to him: any meeting with God is a judgment in itself. Are you ready for the judgment? And can anybody be ready for the judgment?
To meet with God is at the same time joyful and horrible. Joyful because such meeting will delight those who seek for God; horrible because nobody can really be fully ready for such meeting. Insoluble antinomy, which only the Savior Himself is able to resolve. Of course, with our consent.