Swami Vivekananda's illuminative ideas on religion are spread over nearly 4200 pages of his Complete Works. This book containing eight lectures is a compilation from the same and serves as a small introduction to his voluminous writings, talks, and lectures on the subject.
To realize the spirit as spirit is practical religion. Everything else is good so far as it leads to this one grand idea. That realization is to be attained by renunciation, by meditation -- renunciation of all the senses, cutting the knots, the chains that bind us down to matter.
-Swami Vivekananda