Here is an excerpt from B. K. Kiran, Center Incharge, Brahma Kumaris, trying to explain what this tradition actually means:
Raksha Bandhan has a much deeper spiritual explanation. It is a reminder that as souls, we are children of the One Supreme Soul, our Spiritual Father. Its true significance lies in portraying the viceless and pure love between brother and sister. The ‘tilak’ is a symbol of awakening one’s awareness of “Soul-conciousness” – i.e. realization of being a Soul, or divine light energy, and NOT the physical body. It is also a sign of being victorious. Victory here signifies overpowering man’s greatest enemy – the VICES of anger, sex-lust, greed, attachment , ego. Tying a “rakhi” is a symbol of a bond of chastity or purity in thought, word and deed. We face difficulties when we come under the influence of the vices and commit wrong actions.
Here is a social experiment conducted by Varun Pruthi to make a point about the same.
Lets take a pledge to protect every girl like they were our sisters. Will you?