From early times people recognized the importance of the moon, as well as the sun, in helping to produce a variety of weather and a cycle of regular seasons (Genesis 1:14-18; Psalms 104:19). Early calendars were based on the phases of the moon (see MONTH), and so were Israel’s annual religious festivals (see FEASTS). The new moon marked the beginning of the month, and the full moon the middle of the month (Leviticus 23:24; Leviticus 23:39).
The day of each new moon was a holy day on which the Israelite people offered sacrifices and held a feast. Like other holy days, it was announced by the blowing of trumpets (Numbers 10:10; Numbers 28:11; 1 Samuel 20:5; Ezra 3:5; Psalms 81:3; Ezekiel 46:1). The Israelites were guilty of the same wrong attitudes towards the ceremonies of the new moon as towards other religious ceremonies, and as a result God’s prophets condemned them (Isaiah 1:13-14; Hosea 2:11; Amos 8:5; cf. Colossians 2:16; see also SABBATH).
God strictly prohibited any worshipping of the moon. Again there were times when the Israelites broke his commandment (Deuteronomy 4:19; 2 Kings 23:4-5; Jeremiah 8:1-2).