The concept of the only true God is rooted in the Abrahamic religions—Judaism, Christianity, and Islam. In these faiths, God is believed to be the creator and ruler of the universe and the source of all morality and truth. According to the scriptures of these religions, there are no other gods or idols that can compare to God.
However, in many other belief systems, there are multiple gods and goddesses that are worshiped. In these polytheistic religions, such as Hinduism and Shintoism, each deity is believed to have various powers and responsibilities.
From the perspective of the Abrahamic religions, these other gods and idols are not considered to be real or true. They are seen as false idols that can lead people away from the only true God. In the Bible, the worship of other gods is forbidden. In fact, the first of the Ten Commandments for Jews and Christians states, "Thou shalt have no other gods before me."
Despite this, there are some instances where God is depicted as interacting with other gods or idols. In the Old Testament/Hebrew Scriptures, for example, there are accounts of God interacting with the gods of other nations. In some cases, God is shown to be more powerful than these other gods and able to defeat them (Psalm 82 and Exodus 12:12, for example). In other cases, the interaction between God and other gods is more ambiguous.
The New Testament of the Christian bible primarily focuses on the relationship between God and humanity, with Jesus Christ serving as the mediator between God and people. In Christianity, the belief in Jesus as the son of God and the savior of humanity is seen as the key to salvation and eternal life. According to these beliefs, salvation cannot be gained through other gods or through idol worship.
Islam takes an even more unambiguous stance on the relationship between the one true God and other deities. For Muslims, other gods and idols are simply not recognized at all as having any validity or existence. To recognize them in any way is considered to be completely anathema to the Muslim faith.