Two worlds, the same up to a point. Then, divergence.

In our¹ world...

Miriam: "Yosef!² Yosef!" *is crying*
Yosef: "What's the matter, honey?"
Miriam: "I got raped by Roman soldiers, and now I'm pregnant!"
Yosef: "Oh shit. Well... we can't abort, it's against the law. We'll just... we'll just say God did it, and call it a miracle."

In another world...

Miriam: "Yosef!² Yosef!" *is crying*
Yosef: "What's the matter, honey?"
Miriam: "I got raped by Roman soldiers, and now I'm pregnant!"
Both: *Go buy the herb mixture that aborts the child.*
Miriam: *Takes the mixture, aborts the child.*
The world: *Much different, without Christianity.*
God: *Nonexistent*

1 = One possibility, anyway. History doesn't know for certain. I generally favor the theory that Yosef and Miriam were pagan Jews and conceived Yeshuah during some fertility rite in springtime. But this one made for an amusing joke.

2 = Yosef: Joseph. Miriam: Mary. Yeshuah: Jesus (H. C.)