People should be left to believe what they like, so long as they harm no one else. Apart from normal expectations of politeness, it is not however clear why people should require their personal beliefs to be treated with special sensitivity by others, to the point that if others fail to tip-toe respectfully around them they will start throwing bombs.
Nothing is truly unnatural, because everything that exists, including human intelligence, is a product of nature. If human intelligence can devise ways for the genes from two men to result in a child, their doing so is an entirely natural event.
Everybody is entitled to believe. Churches have exactly the same right to exist as a football club, a trade union or a political party. But if you and I set up the Church of the Fairies of the Garden, then I don't think we should automatically be meeting the queen, be entitled to seats in the House of Lords or get public money for our fairy schools.