What is the Maha-Mantra?
Before we understand why we should chant "Hare Krishna," we should probably know what it is that we are chanting.
The maha-mantra is actually two things. First, it is a prayer. We are praying to God and to the energy of God to engage us in devotional service. Basically, to help us reconnect to the spiritual and disconnect from the material. Secondly, it is made up of three names of God.
The word "Hara" is the form of addressing the energy of the Lord, and the words "Krishna" and "Rama" are forms of addressing the Lord Himself. Both "Krishna" and "Rama" mean "the supreme pleasure," and "Hara" is the supreme pleasure energy of the Lord, changed to Hare in the vocative. The supreme pleasure energy of the Lord helps us to reach the Lord.
The maha-mantra is coming from the spiritual platform. Since a spiritual consciousness is higher than a material consciousness, it transcends the sensual, mental and intellectual. Spirit is beyond all of this. The Hare Krishna maha-mantra is our direct connection to reviving our spiritual consciousness. Otherwise, we will just continue in this cycle of pretend happiness, never knowing that we not only deserve so much better than this, but are eternally so much more than this matter, this illusion.
We are spirit, we need a spiritual solution to our problem of materialism. The Hare Krishna maha-mantra is that solution.
No other means of spiritual realization is as effective in this age of quarrel and hypocrisy as the chanting of the maha-mantra:
Hare Krishna, Hare Krishna,
Krishna Krishna, Hare Hare,
Hare Rama, Hare Rama,
Rama Rama, Hare Hare.
These words are different from material words. While material words represent things, the names of God are God. Since God is absolute, He is nondifferent from His names. When you chant "Krishna," that sound vibration is Krishna, God. If this were not so, God would not be absolute, and thus not God. So by very definition, this chanting is God. When you chant, you are associating with God. It's that simple.