A core teaching of the Rebbe:
You must know that you are in this world on a divine mission.
That all that exists and ever existed depends upon your fulfillment of that mission.
And that if any mountain should stand in your way,
Or any ocean block your path,
Or any quagmire detain you from reaching your goal—
Know that you are on a mission from the Creator of heaven and earth.
And if so, it is absurd that any of His creations should stand in the way of the mission for which He has created you.
It could only be that these are not obstacles. Rather, they are a vital element of your mission, designed to lift you higher, and yet higher.
Iterated and expounded in countless talks and letters. For one stark example, see Likutei Sichot, volume 23, pg. 533.
Our mission is to unite to form one harmonious, holy structure, that replicates the interconnected, interdependent qualities of G_d.
Yet it us our differences in qualities, character, opinions that separates us. Our ego demands that I rule, that I am superior to others in everything. I must be the winner. I want to enjoy for myself, control everything. This is our greatest obstacle.
G_d created this selfish quality opposite to His.
Yet this is the weapon He provided us to use against ourself!
By canceling myself - my opinions, thoughts, hatred of others, I can effort to create a space within me to feel and understand others!
Through this concession we rise above this mountain of differences, to come closer to our root, where everything merges become one with our Creator. We create a network through which His light of love can flow between us.
Using our spark from G_d, a desire that awakens to come closer to Him together with our mighty ego concessions we claim:
Mission accomplished