In the biblical context, "altars to the host of heaven" refers to structures built for the worship of celestial bodies, such as the sun, moon, stars, and planets. This practice is explicitly condemned in the Scriptures as idolatry, a violation of the First Commandment, which prohibits the worship of any gods other than Yahweh.

Biblical References:

1. 2 Kings 17:16 : "They abandoned all the commandments of the LORD their God and made for themselves two cast idols of calves and an Asherah pole. They worshiped all the host of heaven and served Baal." This passage highlights the apostasy of the Israelites, who turned away from God's commandments and engaged in the worship of celestial bodies, alongside other forms of idolatry.

2. 2 Kings 21:3-5 : "For he rebuilt the high places that his father Hezekiah had destroyed; he erected altars for Baal and made an Asherah pole, as Ahab king of Israel had done. He also bowed down to all the host of heaven and served them. He built altars in the house of the LORD, of which the LORD had said, 'In Jerusalem I will put My Name.' In both courtyards of the house of the LORD, he built altars to all the host of heaven." This passage describes the actions of King Manasseh of Judah, who not only engaged in idolatry but also desecrated the temple by building altars for the host of heaven within its precincts.

3. Jeremiah 19:13 : "The houses of Jerusalem and the houses of the kings of Judah will be defiled like this place, Topheth—all the houses where they burned incense on the roofs to all the host of heaven and poured out drink offerings to other gods." Here, the prophet Jeremiah condemns the practice of offering incense and drink offerings to celestial bodies, which was prevalent in Jerusalem and Judah.

4. Zephaniah 1:5 : "I will cut off those who bow down on the rooftops to worship the host of heaven, and those who bow down and swear by both the LORD and by Milcom." This verse underscores the syncretism that had infiltrated the worship practices of the people, as they attempted to serve both Yahweh and foreign deities, including the host of heaven.

Theological Implications:

The worship of the host of heaven is consistently portrayed in the Bible as a grave sin, reflecting a departure from the exclusive worship of Yahweh. This practice is often associated with the influence of surrounding pagan cultures, which revered celestial bodies as deities or as manifestations of divine power. The biblical narrative emphasizes that such worship is a direct affront to the sovereignty of God, who alone is the Creator of the heavens and the earth.

Historical Context:

The ancient Near Eastern context provides insight into why the Israelites might have been tempted to worship the host of heaven. Neighboring cultures, such as the Babylonians and Canaanites, had well-established traditions of astral worship, which included the veneration of the sun, moon, and stars. These practices often involved elaborate rituals and were believed to influence earthly events and personal destinies.

Consequences of Idolatry:

The Bible records that the worship of the host of heaven led to severe consequences for the Israelites, including divine judgment and exile. The prophets repeatedly warned that such idolatry would result in God's wrath and the eventual downfall of the nation. Despite these warnings, the allure of astral worship persisted, contributing to the spiritual decline of both the northern kingdom of Israel and the southern kingdom of Judah.

Reform and Restoration:

Throughout the biblical narrative, there are instances of reform where righteous leaders sought to eradicate the worship of the host of heaven. Notably, King Josiah of Judah undertook significant religious reforms, as described in 2 Kings 23:4-5 : "Then the king commanded Hilkiah the high priest, the priests of the second order, and the doorkeepers to remove from the temple of the LORD all the articles made for Baal, Asherah, and all the host of heaven. He burned them outside Jerusalem in the fields of the Kidron Valley and carried their ashes to Bethel. Then he eliminated the idolatrous priests appointed by the kings of Judah to burn incense on the high places of the cities of Judah and in the areas surrounding Jerusalem—those who burned incense to Baal, to the sun and moon, to the constellations, and to all the host of heaven." Josiah's actions reflect a return to the covenantal faithfulness demanded by God and a rejection of idolatrous practices.