Most religions consider sexuality as a gift from God. For example, Christians believe in the story in Genesis 1:27, where God created a male and female who bore children after having a sexual union. Christians, therefore, consider heterosexual as the only way to a healthy sexual relationship. Islam, too believes in heterosexual and despises homosexual practices. Many more religions state that marriage can only be between a man and a woman. In Genesis 2:24, “Therefore shall a man leave his father and mother, and shall cleave unto his wife and be one flesh.” Religion also encourages production and continuity of life, which cannot happen in any other way, aside from the intimacy between a man and a woman. For that reason, many religious people have encouraged heterosexism or homophobia and discouraged homosexuality. For example, in the Catholic church, heterosexuals enjoy seven sacraments while the LGBTQ get six because they do not receive the matrimony.
Additionally, the Pope does not ordain gays or any LGBTQ member as a priest, and other religions also follow the same doctrine. They cannot hold any leadership position in most religious organizations. Most faiths, therefore, make any homosexual relationships a taboo. This religious prejudice is deeply rooted in its culture, and same-sex marital bonding is unacceptable in most religions.
Religions have influentially and actively been in favor of heterosexual majority and against homosexual minorities. Diversity in a sexual relationship has proved the hardest thing for religions to accept for centuries. They play a significant role in encouraging homophobia/heterosexism because sex is sacred and meant for recreation.