eventually a number of countries will develop deliverable nuclear weapons and other means of mass destruction.
Differences in religious beliefs can easily lead to an exchange of these weapons with disastrous consequences at ether a regional or international level.
The logical solution would be a world government with sufficient force (including nuclear weapons) to curtail this threat. Local government would have limited military resources. This government would have to be far more powerful than the existing United Nations organization. The world would be set up with a governmental system similar to the United States with a powerful Federal government and state and local governments with limited power.
The concept of this world government would be almost impossible to achieve. A disaster like a nuclear war between Pakistan and India would have to occur to allow this idea to have even a small chance.
But religious beliefs will in all probability doom this idea. Current religions would have to be replaced by a new world wide religion. The Baha’i faith is one strong candidate.
The Faith’s Founder was Bahá’u’lláh, a Persian nobleman from Tehran who, in the mid-nineteenth century, left a life of princely comfort and security and, in the face of intense persecution and deprivation, brought to humanity a stirring new message of peace and unity.
Bahá’u’lláh claimed to be nothing less than a new and independent Messenger from God. His life, work, and influence parallel that of Abraham, Krishna, Moses, Zoroaster, Buddha, Christ, and Muhammad. Bahá’ís view Bahá’u’lláh as the most recent in this succession of divine Messengers.
The essential message of Bahá’u’lláh is that of unity. He taught that there is only one God, that there is only one human race, and that all the world’s religions represent stages in the revelation of God’s will and purpose for humanity. In this day, Bahá’u’lláh said, humanity has collectively come of age. As foretold in all of the world’s scriptures, the time has arrived for the uniting of all peoples into a peaceful and integrated global society. “The earth is but one country, and mankind its citizens,” He wrote.
http://www.bahai.org/faq/facts/bahai_faith But considering the apocalyptic world view of Christianity and the Muslim faith, it would be extremely difficult to convince devotees of these faiths to convert to a new world wide religion. And while many people simply don't believe in religion, it seems to be deeply ingrained in human personality. It's possible that religion will lead us to our destruction, but most people would refuse to give religion up.
I believe we are going through a test phase for humankind. We are close to developing the technology to travel to the stars, but to do that we have to learn to live with each other. If we can accomplish this, we may encounter other alien civilizations who have passed the test.