Always an interesting topic I think. I'm of the opinion though, that some religions will not accept proof of life outside our planet even if scientists can confirm it. Either via a planets atmosphere through telescopes or closer to home with microbial life by way of a unmanned probe or rover.
No, I think it will take a scenario akin to sci-fi movies like "Independence Day" or "District 9" to convince some hardliners. I have this humorous play in my head of what would happen in that event. I'm always reminded of the scene in the movie Contact when government leaders and politicians are weighing the pros and cons of a message received from space and it's invitation to build a machine. Rob Lowe playing a politically powerful religious conservative leader very contemptuously says to Jody Foster says: "Excuse me miss, we don't even know if these beings believe in god."
Of course all capable countries will be trying to get their intelligence agencies imbedded with visitors should they ever show up. But as I stated above I humorously see politicians and religious leaders scrambling to align themselves with the hopefully peaceful aliens. Any communication with the aliens will be molded to fit the cause. "As you can see from what our new friends have stated the republican parties views are in line with what the rest of the universe believes.' Or " These beings have confirmed our beliefs because they also have the morals our God set forth to guide us, so please send your money to help spread the good news throughout the universe."
Surprised by the poll in this article however, only 37% believe that aliens are out there?? Thought I've seen polls with numbers much higher numbers than that.