Lennon wishes if there is no heaven or hell, all of us are living under the same piece of sky. Lennon sees people are separated by countries, cultures, races, language etc. The conflict between all these factors led a split among people. Besides all these wide conflicts, even some tiny example can become an issue for causing people to stay away from other- the social position, religions, wealth, health, habits, hobby or even the degree of education. Lennon blames the existence of all these inequalities are the reason for why our world running without peace. Lennon deems he is not the only one who have such a hope, he tries to encourage more people to agree his idea about equality can held all of us back together through his song.
Personally I do believe that all the inequalities are the consequence of our jealousy. As we can see, at all times and in all over the world, wars appear mostly because of political conflict and the ambition for gaining more power. Though wars are not common in the 21st century, but we can notice that there are still lots of fights happening between countries. And I am direful to say that nowadays almost 99% of us are willing to help another ONLY because we want to be thanks, be rewarded, and be benefited, rather than just because the other needs help. But I believe this is not what we want to happen, this is why most of the works we assume to happen in the future are usually the creature of Utopia.