Again the PAP IB are up to their rabble-rousing and scare-mongering tactics.
First, gays in Singapore are not fighting for gay marriage. They're fighting for to repeal S377A of the penal code which criminalizes gay sex. In other words, they're fighting for their universal right not to be considered criminals because of their sexual orientation.
Second, if and when Singapore is ready to discuss gay marriage (I may not even see it in my lifetime), then naturally it will involve extensive dialogue with society and majority acceptance before it can be codified into law. Until then, all debate about gay marriage is just a straw man used by fundamentalist Christians to push their homophobic agenda.
Last, there's no forcing. Gays just want the freedom to do what the majority of humans do - form relationships, maybe marry. They're not forcing heterosexuals to turn gay or to marry them. The same can't be said of the majority of Christians – who harass non-Christians into conversion – or Muslims who want to impose Syariah law in secular Western states.