The majority religion of Russia is Russian Orthodox Christianity. This answer can be explained in detail by considering the historical and cultural aspects of Russia. Here is a breakdown of the reasons why Russian Orthodox Christianity is the majority religion in Russia:

1. Historical Background:
- Russian Orthodox Christianity has a long and deep-rooted history in Russia. It traces its origins back to the 10th century when Prince Vladimir of Kiev adopted Christianity as the state religion.
- The Russian Orthodox Church played a crucial role in shaping the cultural and religious identity of the Russian people, especially during the medieval period.
- The church was closely tied to the ruling elite, and its influence extended to all aspects of society, including politics, education, and culture.

2. Cultural Significance:
- Russian Orthodox Christianity has become an integral part of Russian culture, traditions, and national identity. It has influenced various aspects of Russian life, including art, literature, music, and architecture.
- The Russian Orthodox Church has a rich tradition of religious icons, frescoes, and religious ceremonies, which are deeply ingrained in Russian culture.
- Many Russian holidays and festivals, such as Easter and Christmas, are celebrated according to the Russian Orthodox Christian calendar.

3. Geographic Factors:
- Russia is a vast country with a diverse population, and the Russian Orthodox Church has a widespread presence throughout the country.
- The church has established numerous monasteries, cathedrals, and churches across Russia, serving as centers of worship and spiritual guidance for the local communities.
- The influence of the Russian Orthodox Church is particularly strong in rural areas and smaller towns, where religious practices and traditions are deeply cherished.

4. Government Support:
- The Russian Orthodox Church received significant support from the Russian government, especially during the imperial era and the Soviet period.
- Under Tsarist rule, the church enjoyed privileged status as the official religion of the Russian Empire. The government provided financial assistance and granted the church significant political influence.
- Despite the Soviet Union's promotion of atheism and persecution of religious institutions, the Russian Orthodox Church managed to survive and regain prominence after the fall of the Soviet regime. The post-Soviet government has since supported the church's revival and granted it legal recognition.

In conclusion, Russian Orthodox Christianity is the majority religion in Russia due to its historical significance, cultural influence, widespread presence, and government support. It has played a crucial role in shaping the religious and cultural identity of the Russian people throughout history.