It's not enough to connect every man, woman and child to G-d Al-mighty but they must be connected to each other.
Rabbi Hillel and Rabbi Akiva both stated that the commandment to "Love your fellow as yourself" (Vayikra (Leviticus) 19:18) is the greatest principle of the Torah, the fundamental point and everything else is commentary.
How can this be? Wouldn't loving G-d Himself be even more important?
In order love another, a true love, not a love based on a passing thing such as beauty or common interests, etc., you really have to see your soul and make your soul primary in your life, ahead of your body.
And, then, you need to see the soul in the other person. A soul that has the same Divine source as yours.
You might be taller, stronger or smarter than someone else and those are easy to measure. But how about your soul? You have no way to measure your soul against his soul. For all you know his shines brighter than yours.
Elevating the soul as primary over the body is the core point of the Torah and the service of G-d Al-mighty.
Our love for our fellow is how we can measure how real our service of G-d Al-mighty is: how well we are connected with others. That's a reflection of how much we put our soul over our body.
Since that is the entire Torah, then the commandment to "Love your fellow as yourself" is the central principle of the Torah and the central litmus test of how well we are building G-d Al-mighty's vision in the world - a world in which we are all connected to Him and to each other.