Hinduism does not have a concept like non-believers. Everyone in Hinduism is free to follow one’s instinct and is never bonded by Hinduism religion.
As per Bhagavad Gita followers of Hinduism fall into two categories, those believing in Sakaar form of God (having a form) and others following Nirakaar form of God (having no form).
The believers of Sakaar form of God always indulged in religion (rituals) and had nothing to do with spirituality. Rather, religious practitioners did not have much interest in spirituality.
On the other hand believers of Nirakaar form of God always travelled spiritual journey to reach God existing within them in miniscule form as our soul atman, the spirit. Those indulging in spirituality always took inner journey towards the spirit, consciousness existing in heart.
In Hinduism and also Bhagavad Gita one was free to follow any path, that of religion or spirituality. Followers of spirituality also believed in religion. The reason for this is on religious occasions they accompanied the family to places of worship. Such seekers always went to temples as a ritual never for praying or worshipping God.
Travelers of spiritual path always believed that God existed within us in our heart and external worshipping or praying to God was not necessitated.
Hinduism primarily is not called a religion; it is always termed as a way of life. The reason for this is teachings of Hinduism which advocate that human beings guided by their free will can follow any routine in life. On path of spirituality there never is any bondage. Spirituality is one subject that can never be followed under external pressure, for the only reason that everything on path of spirituality always comes from inside.
The best aspect of Hinduism is practitioners of both religion and spirituality believed in God.