I don't believe this event will occur in my lifetime, but who am I to say that it will not.
Do you believe that "humanity can affect the timing"?
Do you believe that humanity should?
No. Certainly, there are some "Christians" who do believe this. Many of them are passive, in that they think Christ will come again when the word of Jesus is know to all nations, and thus they must evangelize to make the Second Coming occur. That's an interesting idea, if an odd one. I wouldn't say its heretical, but like I said, its curious.
However, surely there is a small group who seek to violently bring about the Second Coming. I assume these are the people the "non-religious" are thinking of when they hear people make the claim that they can make the Seconding Coming occur.