I used religion and pink unicorns as my examples. Here is the formula for what I'm describing:
1) Decide what it is that you want people to do that they won't do if asked outright and truthfully.
2) Come up with a two sided dilemma that will arouse people's emotional concern; it must be completely unrelated to cause laid out in 1) but ultimately supports that cause indirectly.
3) Offer two outcomes to this dilemma, one good and one bad, neither of which can be solidly proven or dis-proven for all time. If it can be disputed, you're dead in the water.
4) Impose a time limit, such that if you don't act, you will get the hypothesized bad outcome by default, with the restriction that once you do, it's too late and you don't have the choice anymore.
5) To enforce the idea that it's too late once your limited time offer expires and create a sense of urgency, make that bad outcome something catastrophic and undesirable and unfathomable, something valuable that will irreparably be lost, such that it's "not worth the risk" since you can't prove it can't happen.
6) Likewise, tie in the good outcome as requiring action that achieves the goal laid out in 1) and which guarantees the bad outcome doesn't happen.
7) Seed this dilemma via "education" and popular media until it's a popular and trendy social issue and nobody want's to be the bad guy and take the chance.
8) With enough support, you can now enact legislation that nobody will oppose.
Religion, global warming, terrorism, health care, gun control, oil, etc, all follow this pattern of manipulating both the sense of urgency (same as "limited time offer, call now before you miss out!" marketing methods) and the natural fear of the unknown in people to achieve political objectives.