I believe that some people will go off the deep end just because that's the way those people are.
It's not their fault they are faithfully loyal to the wrong source.
God and religion are not the same thing.
Religion is beliefs, practices and ideas about God based on human history and superstition, manipulation of masses of people for dollars and control.
Fear and desperation fuel religion as well as belief.
Although religion changes, God never does.
When people find out what the other races of people have to share with us of knowledge and technology, the people will be angry that our leadership has kept us denied a greater quality of life.
The leaderships of the richest, most influential nations and religions depend on, exploit and maintain the lucrative suffering of their people.
All the known races of people in all the known universes believe in the one same God as creator of all life.
This is because God teaches at every world.
I think that people will react based on the way those people are, not based on what they are reacting to.
It always takes some time for new things to sink into society.
Then, the people act like they always knew the nature of it.
Don't worry about the people who will "never" accept the visiting races - their stubbornness goes away with them.
What they think today bears no factor on what will come to be.
Generations turn over and new people embrace what was blasphemy to their elders and ancestors.
Science only continues to lend further normalcy to nature, not less.
Religions will continue to change as always.
Religious people will change by generation with their religions. 
Mass confusion about it, rampant disinformation, framing for crimes.
True understanding across our planet is going to take a long time, though it will begin immediately also.