One of the primary responsibilities of the priests in Israel was to teach the people God’s Word so
the people could apply that knowledge to their lifestyles, values, worship and civil responsibilities. 
In Hosea’s day (around 740 BC) Israel’s clergy, the Levitical priesthood who were the
custodians of the Law of God and teachers of God’s Word, had “rejected knowledge” of God
and his Truth as revealed in the Law and Prophets. The priests had replaced Gods’ Word
with local idols and foreign Baals which brought corrupt morals, false realities and twisted
political alignments.  God says he has “rejected” these priests because they have “rejected” knowledge. And, because the priests had “ignored” (Hb. sakah, “forgotten”) God’s law,
God would likewise “ignore” (sakah, “forget”) the “children” of the priest. The national leadership
of the priesthood could be considered the “mother,” which means her “children” would refer
to the citizens of the nation.  The reference to “children” refers to the people of Israel and
probably does not refer directly to the next generation of the priests or the community
in this case, although the next generation  would also suffer from being indoctrinated
with the deception and ignorance of the priesthood.

Not only would the corrupt priest be rejected and ignored, but the people they ministered
to still remained in ignorance. This lack of “knowledge” (Hb. hadda’ath “the knowledge”  
with the definite article connects it to da’ath elohim “knowledge of God” in 4:1) among
the common man in Israel would naturally result in destruction.  The people who had
listened to the corrupt clergy in Israel in 740 BC would be “destroyed” (Hb. damah “ruined”)
in 723-721 BC by the Assyrian invasion and deportation. Isaiah states the same principle
in Isaiah 5:13, “my people will go into exile for lack of understanding.”