Contradiction with Exodus 20:3
This verse commands that there should be no other gods before God, contradicting 1 Samuel 5:5 which acknowledges the physical presence and reverence for another deity's space.
Exodus 20:3: Thou shalt have no other gods before me.
Contradiction with Isaiah 45:5
Explicitly states that there is no God besides the Lord, contradicting the acknowledgment of Dagon's temple.
Isaiah 45:5: I [am] the LORD, and [there is] none else, [there is] no God beside me: I girded thee, though thou hast not known me:
Contradiction with Deuteronomy 6:14
Prohibits following other gods, contradicting the acknowledgment implied in 1 Samuel 5:5 by the ritual observed regarding Dagon.
Deuteronomy 6:14: Ye shall not go after other gods, of the gods of the people which [are] round about you;
Contradiction with Psalm 81:9
God instructs that there should be no strange god among His people, contradicting the recognition of Dagon's shrine.
Psalm 81:9: There shall no strange god be in thee; neither shalt thou worship any strange god.
Contradiction with 1 Kings 18:21
Calls people to choose between the Lord and other gods, highlighting a contradiction with the context of respecting the space of another god's temple.
1 Kings 18:21: And Elijah came unto all the people, and said, How long halt ye between two opinions? if the LORD [be] God, follow him: but if Baal, [then] follow him. And the people answered him not a word. [opinions: or, thoughts]