Mantra is a vehicle for expansion of energy, a tool that helps us to transcend our mind. We usually associate it with new-age practices or Yoga classes, but the origin of Mantra is ancient and deeply rooted in our DNA. Our ancestors, regardless of their origin, used mantras as a tool for improving their energy.
There are many different mantras with various forms. For me, the cross faith correlation is fascinating and in particular, the Tantric mantras and the Kabbalistic mantras. One great example is what is known as the 72 names of God.
Although the Bible express all the different titles of God, the 72 names of God represent a unique perspective of invoking distinct characters.
In the science-based Western society, scientists are beginning to see that everything in existence is vibration. Different objects vibrate at different frequencies and hence manifest differently in the physical world. This idea has gained much popularity in the recent decade and has become more mainstream than ever. One of these theories is the string theory, which was described elegantly by Professor Michio Kaku;
"In string theory, all particles are vibrations on a tiny rubber band; physics is the harmonies on the string; chemistry is the melodies we play on vibrating strings; the universe is a symphony of strings, and the 'Mind of God' is cosmic music resonating in multidimensional hyperspace."
He beautifully describes what the Indian Rishis and the people of the Middle East knew for thousands of years. Everything in nature is vibration, the more complex the wave, the more visible it will be to us.
When we sound out a vibration, we deliberately increase its value, which creates ripples in nature's fabric. When this vibration is consistently "playing", it will eventually alter and rearrange nature around us to support the new wave.
In Tantra, for example, we invoke different Goddesses or different qualities of nature. We deliberately generate specific traits by using intention, focus, and Mantra, which is essentially vibration.
It is told that Moses did the same, he used the 72 names of God to lead the Israelites out of Egypt, part the Red Sea and cross the desert.
When we pray to God in the Synagogue or Church, we do the same. We invoke different aspects of the Divine.
In Hebrew, at times, we use "Ein Sof" (the endless one) or "El Shaddai (God all Mighty) to invoke different aspects of the Divine, and sometimes we even invoke Angels to obtain from their energy.
The 72 names of God is one of the most interesting Kabbalistic mantras that I know of. Each combination of 3 letters generates a different vibration and when the practitioner meditates on them, he opens up to the various dimensions of these energies. These three-letter words are a doorway to different transcendental experiences that benefit the practitioners with different strengths. In the Yogic world, we know them as Siddhis or spiritual powers.

So regardless of your personal path, the true reality of nature is the same. Our reality is made up of vibrations, that when invoked, generate a response.
Your reality is a sum total of the vibrations that you have generated. Nature will always verify your inner state, your inner beliefs.
Like when you throw a rock in a calm ocean, it will just respond with ripples, with love, without any resistance or judgment.
So be aware of your thoughts, beliefs and speech as you literally generate your own existence.