Deuteronomy 5:6 - 7
ESV - 6 'I am the Lord your God, who brought you out of the land of Egypt, out of the house of slavery. 7 'You shall have no other gods before me.
For follow-up discussion and general commentary on the topic. Comments are sorted chronologically.
Because it was an abomination to God for Israel to have other god. The God of Israel is the only true and living God;all the other so-called gods were false as they could not see, hear, speak or perform. They were also made of wood or precious metal which the only true and living God created. Praise God !