This concept gained traction during the reign of Ivan III, who sought to establish Moscow as a powerful and influential political entity. He married Sophia Palaiologina, the niece of the last Byzantine emperor, which further strengthened the connection between Russia and the Byzantine Empire.
The idea of Moscow as the Third Rome was expressed through various religious and cultural symbols, such as the construction of churches and monasteries in a Byzantine style, the adoption of certain Byzantine ceremonies, and the use of religious rhetoric that drew parallels between Moscow and ancient Rome.
However, it's important to clarify that the concept of Moscow as the New Jerusalem was not widely embraced outside of certain religious and political circles. It remained primarily a symbolic and ideological notion, rather than a literal claim to being the New Jerusalem.