Throughout history, many cultures and religions have had gods associated with fire. These deities often represented the power, destruction, and transformative properties of fire. In some cases, fire gods were considered to be the most powerful and revered deities in their pantheon. However, it is difficult to determine who the strongest fire god is as different cultures have their own unique beliefs and mythologies surrounding these deities.

In Hindu mythology, the god Agni is often considered the god of fire and is revered as one of the most important deities in the Hindu pantheon. Agni is said to represent the transformative properties of fire and is associated with purification, sacrifice, and spirituality. He is also believed to be the messenger of the gods and is said to convey offerings from humans to the gods. In Hinduism, Agni is considered to be the most powerful of all the gods, and his flames are believed to be eternal and all-consuming.
In Norse mythology, the god Loki is often associated with fire. Loki is considered a complex and sometimes controversial figure in Norse mythology, but he is also associated with transformation, trickery, and change. He is often depicted as a shape-shifter and can transform into various animals, including a serpent, which is associated with fire in Norse mythology. Loki is also associated with chaos and is believed to have a hand in Ragnarok, the final battle of the gods.
In Greek mythology, the god Hephaestus is often associated with fire. Hephaestus was the god of metalworking and craftsmanship, and his forge was said to be located beneath a volcano. He was often depicted with a hammer and anvil, and his creations were said to be of the highest quality. Hephaestus was also associated with fire and was said to have the power to control and manipulate it. However, in terms of strength and power, Hephaestus was not typically considered one of the most powerful gods in the Greek pantheon.
In Aztec mythology, the god Xiuhtecuhtli is often considered the god of fire. Xiuhtecuhtli was associated with both the destructive and transformative properties of fire and was also believed to be the god of time and the calendar. He was often depicted as a skeletal figure, and his flames were said to be the source of life and regeneration. In Aztec mythology, Xiuhtecuhtli was considered one of the most powerful and important deities, and his worship was an important part of Aztec religion.
In Shinto mythology, the god Kagutsuchi is often considered the god of fire. Kagutsuchi was associated with volcanic activity and was believed to be the cause of earthquakes and eruptions. He was also believed to have the power to control and manipulate fire, and his flames were said to be extremely destructive. Kagutsuchi was often depicted as a serpent or dragon, which are also associated with fire in Japanese culture.
Ultimately, determining the strongest fire god is a matter of interpretation and perspective. Different cultures have their own unique beliefs and mythologies surrounding fire deities, and the power and significance of these deities can vary widely depending on the context. While some fire gods are believed to be all-consuming and all-powerful, others may be associated with specific aspects of fire or may be considered less powerful than other deities in their pantheon.