Nothing short of a major plague has the ability to unite the human race and bring them together in support of a common cause, as does the prospect of making contact with an alien race.
Alien beings with the ability to reach the Earth from possibly millions of light years away could provide us with the answers to many questions and solutions to many problems faced by the human race as a whole. Assuming they've been around as a race far longer than we, the extent of their knowledge could offer us untold opportunities for advancement as a race, and as individuals.
The human race might be exposed to fantastic technologies, great philosophies, advanced medicine and answers to some of the greatest mysteries of the universe, such as the existence of a higher being, the true age of the universe and insight into what else is out there and if there is potentially more beyond that. We might learn to harness new energies or to prevent global warming. We might simply find another consciousness as eager as our own to solve the mysteries of life and of the universe.
We are ready for this. Indeed, we need it. We are eager for answers and for a cause to unite us. That cause could be to present the best of the human race; to our visitors and to one another. That cause could be to save ourselves, or the entire universe from destruction. That cause could be the simple desire to learn, a desire that could spark a new age of interest and development for humanity; a renaissance that transcends geography, religion and greed.
Suppose the alien visitors have greatly superior militaristic technologies and intend to enslave us or destroy us completely. Would this not also be a uniting prospect?
If they are out there and they want to come, they will. Just as the day will come when our sun will die, or when an asteroid of incredible size will smack into our home planet. Our end may or may not be predetermined and we sill surely never be ready for it. But ready or not for the end, we are ready for answers. We are ready to be exposed to the full splendor and wonder of our universe. If it takes an alien race to lead us to them, we are ready for that too.