Among the variety of functions of the national idea as an important part of the modernization processes, one can single out its significance as a historical constant, an imperative defining the goals of the national-state organism. From the position of the epistemological ideal, it is possible to analyze and evaluate various national ideas, since the true effectiveness of a national idea depends on its historical adequacy. Within the framework of five stages of the history of the formation and evolution of the Belarusian national idea during the late XVIII – first decades of the XXI century, the last of which is not completed, the cultural and civilizational confrontation of the Polish-Catholic (and later the entire Western) and the Russian-Orthodox world manifested itself. As a result, today there are three competing approaches to the definition of Belarusian national identity – the Western-Russian-pro-Soviet (which has an obvious advantage in terms of rational validity and historical authenticity), the Litvinist and hybrid (dualistic). The complex of the main myths of Litvinism, refuted within the framework of his-torical analysis, includes the concepts of the cultural and state development of Belarus isolated from the rest of the principalities of Ancient Russia in the XI – XIII centuries, the non-Slavic (Baltic) ethnic origin of Belarusians, the great cultural development and a high degree of legal democracy of the Belarusian society under the rule of Lithuania and Poland, its significant linguistic and the cultural difference from Moscow Rus, the decline of the Belarusian lands after their incorporation into the Russian Empire, the genocide of Belarusians on the initia-tive of Moscow in the XVII and XX centuries. The condition for completing the formation of a full-fledged na-tional idea in the Republic of Belarus is the rejection of the artificial construction of parallel history, the use of Western-centric cultural stamps, fetishization of what has no real relation to its national-state formation. A pro-ductive methodological principle of studying the past of Belarus can be the identification of the history of the Belarusian people and the history of Polish-Lithuanian subjects and institutions, as well as an objective as-sessment of the processes and consequences of foreign expansion into its territory.