Realisation of love can never come so long as there is the least desire in the heart, or what Shri Ramakrishna used to say, attachment for Kâma-Kânchana (sense-pleasure and wealth). In the perfect realisation of love, even the consciousness of one's own body does not exist. Also, the supreme Jnana is to realise the oneness everywhere, to see one's own self as the Self in everything. That too cannot come so long as there is the least consciousness of the ego (Aham).
Mankind ought to be taught that religions are but the varied expressions of THE RELIGION, which is Oneness, so that each may choose the path that suits him best.
The Tao gives birth to One. One gives birth to yin and yang. Yin and yang give birth to all things... The complete whole is the complete whole. So also is any part the complete whole... But forget about understanding and harmonizing and making all things one. The universe is already a harmonious oneness; just realize it.