Nobody can change someone who doesn’t want to change. Otherwise God would not have already done the needful and there would have been no need of any yoga or sadhana etc. The evolutionary design or the law of evolution in human beings operates through conscious choices. Most people do really want to change and do little by way of effort in that direction. They may say that they want to change but they are expecting a miracle. There is lack of a sincere will, often a justification for the defects of nature. In fact it is more true that if someone is really determined to change and is ready to persevere and persist despite all the difficulties then nothing can stop the change from coming. Of course there is a process to it and time is needed especially if the difficulty is deep rooted. Yet the maxim that victory comes to the most persevering and enduring is indeed very true. This is the experience of all who have walked the way long enough. It is too early for you to declare that change is impossible.
As to Ravana, he never wanted to change. His bhakti was tainted with ambition and lust for power as indeed all Asuric bhakti is so motivated. There was insistence and never any surrender. Still Shiva did try to caution him about mending his ways but instead of listening to his Aaradhya, Ravana chose to abandon him rather than mend his ways. The Divine leads, He does not drive, He guides but does not compel. Ravan chose to be driven by his ego rather than Shiva, he chose to be guided by his ambition rather than the Divine.
At the same time there are number of instances of conversion and change when someone accepted the Divine leading. Ravan is not the only example of a bhakta, if at all he was one. There is Valmiki, Jagai and Madhai, Augustine, Angulimaal and many others who changed. Here itself, in Sri Aurobindo Ashram, i know of devotees who changed. It is all a question of sincerity of aspiration, a faith and will that persists despite downslidings and genuine surrender full of trust in the Divine. When these things are missing or the person not willing to develop then obviously the change is postponed because, in the last analysis, the change can be delayed but not denied unless one is too impatient and quits the game like Ravana.
Affectionately,
Alok Da
