No. I don't think so. It's a negative aspect of human nature that we tend to separate ourselves based on our differences rather than overlook them and embrace unity. We separate ourselves based on belief, economic class, education level, and, sometimes, just the color of our own skin.
There is only one human race - biologically speaking. Once you understand that it might be possible. But yes, people will always hate each other over differences. Prime example are members of abrahamic religions. They come from different ethnic groups and are killing each other daily.
If aliens prove to exist and they come to attack us, they will be united. Looking back our history, political leaders have united the whole nation by making people conscious of outer enemies. Similar situation will happen worldwide.