Pancasila, as the source of all sources of state law, is the result of deep exploration, analysis, and reflection by the founding national figures of the Republic of Indonesia. All aspects and values of civilization, history, geography, demography, religion, ethnicity, culture, customs are united in five basic values (grand norm), and each value which is one with other values is an inseparable unity. Terrorism and radicalism are real threats to the existence of Pancasila as an ideology. It takes consistency, awareness, and strong determination from all elements and components of the Nation to replace the ideals of Pancasila law in building every order of national and state life through statutory regulations because Pancasila is the best vaccine in building immunity/deterrence of the Indonesian people from individuals. Radicalism and terrorism and other ideologies.The Pancasila philosophy must continue to be echoed and transmitted in every statutory regulation made, starting from the highest to the lowest provisions, and implemented in the attitudes and legal behavior of the community. This paper was written using the statute approach, the case approach, the historical approach, and the conceptual approach. After the materials have been collected, a study or analysis is carried out using a qualitative prescriptive and normative approach according to the legal issues raised. The purpose of this paper is to present a comprehensive scientific study on the threat of radicalism and terrorism to the existence of Pancasila as the State Ideology and legal philosophy conceptions, placing Pancasila as the source of all sources of state law as reflected in every existing statutory regulation and legal practice to cut the eyes of radicalism and terrorism in Indonesia.