Hosea 8:

Apostasy of Israel – Hypocrisy of Israel.

Destruction threatened for the impiety of Israel. (1-4):

V. 1.…trumpet… Trumpet will sound when the enemy’s attack is imminent. Eagle… Eagle/vulture is a symbol of aggressor. So the Assyrians arrival will be imminent on the appointed day.
…they have transgressed My covenant…
Note that he says “transgressed,” not “annulled” (cf. 6:7). The Lord had not “annulled” his covenant with Israel; she was still his estranged wife. While it was a foregone conclusion that Israel would violate the covenant, provisions for reconciliation were put in place (Lev. 26:40–45; Deut. 31:27–29; cf. Deut. 30:1–10). ESV Study Bible.

V.2…cry…’My God, we know You!’ … This chapter is a response to Israel’s cry. They say they know God, but God says it is hypocritical. God is exposing the idolatry, corrupt politics, and false worship of the nation. Knowing God it self is not sufficient. We need to love Him, follow Him, cleave Him and serve Him.
V. 3.…enemy will pursue… Explaining the reference to eagle/vulture in verse 1.
V. 4.…set up kings…made princes,…made idols… Their leaders are not God’s choice.
I knew it not.
Hosea and his readers were well aware that God knows everything; the point is not whether God was aware of the princes they had set up, but rather, that the people had never asked him for guidance before choosing these leaders. – ESV Study Bible.

Destruction threatened for their idolatry. (5-10):

Vs. 5&6.… calf is rejected…a workman made it… The calf, the idol of Israel will be broken into pieces 2 Kings 23:15.
V. 7…reap the whirlwind.… Anything we sow in small amount, we will reap in abundance.
Vs. 8 – 9.…like a wild donkey… Israel was wandering independent of God like a wild donkey. However, Israel is like a wild donkey in terms of ‘depending on God.’
V. 10…they have hired among the nations… Israel is like a wild donkey only in terms of not being dependent on God. However, Israel was dependent on the nations. …burden of the king…But the foreign armies ravaged the land and levied heavy Tribute. Israel sought to obtain by purchase what God had freely promised; His protection and provision.
They promised themselves plenty, peace, and victory, by worshipping idols, but their expectations came to nothing. What they sow has no stalk, no blade, or, if it have, the bud shall yield no fruit, there was nothing in them. The works of darkness are unfruitful; nay, the end of those things is death. The hopes of sinners will deceive them, and their gains will be snares. In times of danger, especially in the day of judgment, all carnal devices will fail. – M. H. Concise commentary.

Further threatenings for the same sins. (11-14):

It is a great sin to corrupt the worship of God, and will be charged as sin on all who do it, how plausible whatsoever their excuses may seem to be. The Lord had caused his law to be written for them, but they cared not to know, and would not obey it. Man seems by the temples he builds to be mindful of his Maker, yet really he has forgotten him, because he has cast off all his fear; but none ever hardened his heart against God and prospered. As long as men despise the truths and precepts of God’s word, and the ordinances of his worship, all the observances and offerings, however costly, of their own devising, will be unto them for sin; for those services only are acceptable to God, which are done according to his word, and through Jesus Christ. – Matthew Henry Concise Commentary.

V. 11…because Ephraim has made many altars…become…altars for sinning.… Adding idolatrous altars increased their transgression, rather than remitting it.
V. 12…written for him.. God has written His Law by Moses first, by other prophets afterwards. But they were counted as strange thing to them.
…great things… Can we disregard those great things? Do we doubt those great things? Ps. 119:18, 54, 92, 136, & 165.
V. 14…forgotten his Maker, And has built temples;… What is the use of building Temples, while we have already forgotten the Creator? …Judah also has multiplied fortified… Judah started trusting her armaments while Israel trusted in their religious shrines. devour his plalaces… The efforts and trust of both Israel and Judah will be proved futile.