Mandate from God? I disagree. Where does this stuff come from?
On your second point, I think they're claiming that only in this last election. I would guess that prior to this last election, both parties had a fairly equal number of complaints about the other party cheating, assuming we're not talking about just presidential elections.
Ironically, the same Democrats, media, etc., who guaranteed the American people that the 2016 election had been not just meddled in, but that (since proven false) collusion had taken place between the Trump campaign and Russia, are now assuring us that the last election was entirely secure. This in spite of many states illegally enacting rules changes that even Stevie Wonder could see would make it easier to cheat. That almost seems somewhat circumstantial in terms of how they feel about election security.
That having been said, I'm not saying there was cheating, or massive fraud, or whatever the catch phrase is, because so far it hasn't been proven. Although, as a general rule, if something can happen, it will.