How else can you convince a layperson at all?
How do you make other people do what you think they should do? You don't.
You tell them what you're sure is true with a simplified explanation of why using the language of certainty. Then you tell them what you believe to be true and why, using the language of uncertainty. Then you acknowledge any competing theories that haven't been strictly disproven, again with the language of uncertainty, and briefly discuss the merits behind those points of view.
Anyone who needs to make a decision on that information will then ask their personal subject matter expert to spot check you -- do any of your certain claims appear questionable? Does any of the uncertainty in your beliefs appear to be mere wishful thinking? Did you deliberately omit the competition?
Folks won't make their decision on the facts. They'll make their decision based on whether they believe you're honest. Behaving like a used car salesman, using the language of certainty for everything you believe and ridiculing that which you don't, dissuades folks from finding you credible. The hard sell sometimes achieves a single result but it never achieves sustainable results over time.