One might think that if this is the case for one who has been saved from physical danger, then surely one who is saved from spiritual disaster would be similarly encouraged to celebrate his escape. But that is not the case. The Chatam Sofer explained in his notes on the Shulchan Aruch that in fact, the proper way to commemorate such occasions is to hold a 'personal Yom Kippur' on the day that one rectified their ways by fasting, confessing their sin and pledging to continue on one's new path. Why is this so? Surely a spiritual redemption is one a higher level than a "mere" physical one and deserves no less of a celebration?
The Chatam Sofer explains this seeming discrepancy by noting that the two situations are inherently dissimilar and therefore require different treatments. When one experiences physical danger, typically it is an external matter, a result of time and place. Once the circumstances change, the danger passes and may well not return. As such, we may celebrate God's role in removing this danger from us. But spiritual danger is entirely different. Spiritual danger occurs within us, depends on our own state of mind and as such, we can not ever be sure that we are truly past it. As Hillel teaches us in Pirkei Avot, "ואל תאמן בעצמך עד יום מותך," meaning "Do not believe in yourself until the day of your death."
Spiritual danger, the Chatam Sofer teaches us, is something that we must contend with endlessly. It is important to celebrate our victories - if we discipline ourselves into being more patient or honest, or if we force ourselves to stop making the same mistakes we used to make over and over - these are important achievements that we should be proud of. But it is also important for us to keep at the forefront of our minds that these character flaws are not easy to rectify and are liable to reappear. In order to truly better ourselves and ensure a proper T'shuva, we must not allow ourselves to feel too comfortable. Hopefully we will all merit to accomplish a genuine, complete T'shuva for our flaws, make ourselves better people and in turn, the world a better place.
From Jerusalem, have a meaningful and easy fast.