Beware "history has shown" claims building on thin anecdotes! The image macro claims that dictatorships regularly ban religion and private firearm ownership, and indeed, that they do so before anything else. The heavy implication is that gun control and atheism lead to dictatorship. Before evaluating that claim, let's ask, as an initial matter, which "totalitarian governments" are we analyzing?

Well, firearms and by extension private firearms are relative latecomers to history, and depending on how you define the term, so are "totalitarian" regimes. Perhaps the author is really only talking about the 20th century: if so, he's essentially playing with a stacked deck, since the most notable dictatorships of the last century were communist, and definitionally atheist. Noting that most modern dictatorships were atheist therefore conveys no information: it's a correlation, yes, but repressed religion was the result not the cause of the dictatorship. So much for the religious aspect.

As to guns, this has been discussed here before. In brief, any causal link between gun control and tyranny is doubtful, especially in the case of Nazi Germany, where the Nazi party actually liberalized gun laws.