His comments were made even before the Russian contestant was banned from this year's competition.
He went even further to compare it with Sodom and Gomorrah.
In a conversation with the BBC, Mr Milonov said: "Eurovision became a disgusting socialist nightmare for all these left-wing parties with all their bearded women, or men, with these anti-Christian positions".
"I am sure that most conservatives in the world will never attend this festival. Because this is a festival of Sodom and Gomorrah."
Russia will not participate in this year's competition, for the first time in 42 years, after a ban imposed by the hosts Ukraine. Russia was barred because, in 2015, in violation of Ukrainian border rules, Russia's representative, Julia Samoilova performed in Crimea, the Ukrainian peninsula annexed by Russia a year earlier.
This is the first time in Eurovision history that the host nation has barred another country's singer.
"When the rumours began I might not go, I was so sad," she told the BBC in Moscow. "I thought, how come? This was my dream. When the final decision was taken I didn't believe it. But unfortunately, this is the reality."
Eurovision's Executive Supervisor Jon Ola Sand said that Ukraine's decision went "against both the spirit of the contest and the notion of inclusivity that lies at the heart of its values".
In an unprecedented move, the EBU offered Russia the chance to take part by satellite from Moscow but they declined.