All of the three sentences below have about the same force and are a good renderings.

• Il n’y rien de moins vrai.
• Il n’y a rien de plus faux.
• Rien n’est plus invraisemblable.

There are other possibilities;

• C’est de l’absurdité la plus complète. (In cases when what is false is at the same time seen as blatantly illogical.)

The literal translation works here : “Rien n’est plus éloigné de la vérité”

The French can be more blunt in expressing themselves and short forms are a possible way to achieve this; the present case calls, as I see it, for just such a form.

« Ceci est faux » would probably be the closest.