In addition, many predictions based on the idea have led to additional observations that support it. This idea of the origin of the universe is best classified as a

This would be classed as a theory. The statement is considered as close to iron-clad as can be seen in the world of scientific inquiry, and is used to spawn additional findings and is used as the basis for these findings. The findings can be replicated and have yet to be refuted by any reputable sources.