Question: "What was the significance of the new moon in Bible times?"
Answer: The significance of the new moon in Bible times is that it marked the beginning of a new month (the Hebrew calendar is lunar-based), and it was a time when the Israelites were to bring an offering to God. The beginning of the month was known not by astronomical calculations but by the testimony of messengers appointed to watch for the first visible appearance of the new moon. As soon as the first sliver was seen, the fact was announced throughout the whole country by signal fires on the mountaintops and the blowing of trumpets. The Hebrew word for “month” (hodesh) literally means “new moon.”
In Numbers 28:11, the New Moon offering is commanded for the first time: “On the first of every month, present to the Lord a burnt offering of two young bulls, one ram and seven male lambs a year old, all without defect.” Each of the animal sacrifices was to be accompanied by a grain offering and a drink offering (verses 12–14). In addition to burnt offerings, a goat was to be sacrificed to the Lord as a sin offering (verse 15). The New Moon festival marked the consecration to God of each new month in the year. New Moon festivals were marked by sacrifices, the blowing of trumpets over the sacrifices (Numbers 10:10), the suspension of all labor and trade (Nehemiah 10:31), and social or family feasts (1 Samuel 20:5).
As with any religious ritual, there was a danger of observing the New Moon festivals without a true heart to follow God. Later in their history, the Israelites continued to observe the New Moon festivals outwardly, even after their hearts had turned cold toward God. They readily parted with their bulls and lambs and goats, but they would not give up their sins. They relied on the outward observations to cleanse them, even though there was still evil in their hearts. God had severe words for such hypocrisy: “Stop bringing meaningless offerings! Your incense is detestable to me. New Moons, Sabbaths and convocations—I cannot bear your worthless assemblies. Your New Moon feasts and your appointed festivals I hate with all my being. They have become a burden to me; I am weary of bearing them” (Isaiah 1:13–14). Sin is hateful to God, and no amount of ritual or ceremony or sacrament can make up for a sinful heart. “Behold, you delight in truth in the inward being” (Psalm 51:6, ESV; see also Hosea 6:6).
Observance of New Moon festivals and their sacrifices is no longer required. When the perfect Sacrifice, the spotless Lamb of God, appeared, He rendered the observation of these ordinances no longer necessary. All the righteous requirements of the Law were fulfilled by Him (Matthew 5:17), and His work on the cross means that no longer are sacrifices for sin required. Paul reminds us of this fact: “Do not let anyone judge you by what you eat or drink, or with regard to a religious festival, a New Moon celebration or a Sabbath day. These are a shadow of the things that were to come; the reality, however, is found in Christ” (Colossians 2:16–17).