By 2020, with the continued growth rate, Muslims will account for one-fifth of the entire population.
Their numbers continue to grow, fed by immigration from largely Muslim, former Soviet republics in the North Caucasus and Central Asia.
Islamic leaders have said that Russia is a haven for Muslim immigrants, keen to work and build on their growing community, and they discount the rise of hostile nationalist sentiment.
"When they say Russia is for Russians, it’s a mistaken path that could lead to the break-up of the Russian Federation"
Damir Gizatullin, Council of Muftis
Damir Gizatullin, from the Council of Muftis, said: "Some irresponsible politicians want to achieve electoral success by creating nationalist waves.
"When they say Russia is for Russians, it's a mistaken path that could lead to the break-up of the Russian Federation."
Many ethnic Russians are terrified at the prospect of becoming a minority in their own country.
Alexander Belov, from the Movement Against Illegal Immigration, said: "History is a fight between races and religions.
"It's the law of nature ... people are used to being with people like themselves, speaking the language their mothers taught them."
The Orthodox Church, restored since the Soviet collapse, remains dominant in Russia.
But with the rise of Islam, coupled with the negative growth in Russia's ethnic Slav population, dramatic change is under way.
If the trend continues, the Muslim population could outnumber ethnic Russians within 30 years.