The new moon is the first visible crescent. The word “month” as found in Exodus 12:2 is derived from the Hebrew “chodesh,” meaning, “new moon.” The root of chodesh, Hebrew “chadash,” means to be new or to rebuild. Historically the Jews determined the month by the first visible crescent: “The Hebrew or Jewish calendar had three stages of development: the preexilic, or Biblical; the postexilic, or Talmudic; and the post-Talmudic. The first rested on observation merely, the second on observation coupled with calculation, and the third on calculation only. In the first period the priests determined the beginning of each month by the appearance of the new moon” (International Standard Bible Encyclopedia, “Calendar”). Yahweh uses the new moon to establish moedim, or commanded observances, Psalm 104:19. Special offerings were also given on the new moons, 2Chronicles 2:4; 8:13;23:31. We find many references to the new moon or beginning of months in the Scriptures, including the obligation for True worshipers to observe them, Numbers 10:10; 28:11-15; 1Chronicles 23:31; 2Chronicles 2:4; 8:13; 31:3; Ezra 3:5; Ezekiel 46:1, 3, 6;Colossians 2:16. Apostolic Believers, who remained true to His Word, continued to honor new moon days as well as observe Feast days in the New Testament, Acts 18:21; 27:9; 1Corinthians 5:7-8. Further, we learn from Ezekiel’s prophecy (46:3) that new moon days will be kept in the coming Kingdom: “The people of the land shall also worship at the doorway of that gate before Yahweh on the Sabbaths and on the new moons.
For an in-depth study on the new moon read our booklet: What Is a Biblical New Moon