Ramakrishna's main teachings included God realization as the supreme goal of life, renunciation of Kama-Kanchana, Harmony of Religions and Jiva is Shiva. Key concepts in Ramakrishna's teachings included the oneness of existence and the unity and truth of all religions.
"It is said that truthfulness alone constitutes the spiritual discipline of the Kaliyuga. If a man clings tenaciously to truth he ultimately realizes God. Without this regard for truth, one gradually loses everything. If by chance I say that I will go to the pine-grove, I must go there even if there is no further need of it, lest I lose my attachment to truth. After my vision of the Divine Mother, I prayed to Her, taking a flower in my hands: 'Mother, here is Thy knowledge and here is Thy ignorance. Take them both, and give me only pure love. Here is Thy holiness and here is Thy unholiness. Take them both, Mother, and give me pure love. Here is Thy good and here is Thy evil. Take them both, Mother, and give me pure love. Here is Thy righteousness and here is Thy unrighteousness. Take them both, Mother, and give me pure love.' I mentioned all these, but I could not say: 'Mother, here is Thy truth and here is Thy falsehood. Take them both.' I gave up everything at Her feet but could not bring myself to give up truth." -Sri Ramakrishna