From the time you are born, your naming ceremony, your marriage ceremony and death ceremony are all according to religion. But spirituality is anything that uplifts life. So even though yoga, meditation, etc., are born out of the ancient tradition, it is a way of life and it is not a religion per say.
Someone asked the president of India Dr. Sarvepalli Radhankrishana who is a Hindu, the definition of the Hindu religion. He said, 'There is no way you can define Hinduism. It is just a way of life.'
So because there are so many religions, the way of life also came to be known as a religion, otherwise Hinduism is not a religion, it is just a way of life.
So these chantings have an impact on our system, on our mind, and our consciousness. The older the chants, the more it impacts the deeper levels of our consciousness. That is why it is said to chant Om.
It is not Krishna or something, but it is the value of the mantra that is most important.