What does it mean that every Jew has a spark of the soul of Moshiach?

In order to answer this question, we must first understand what the Jewish soul is.  The Midrash writes:  “There are five names for the soul:  Nefesh, Ruach, Neshama, Chaya and Yechidah.”  These five names, as explained in the teachings of Chassidut, are not simply words.  Rather, each one reflects a different level and aspect of the soul.

The first four (Nefesh, Ruach, Neshama and Chaya) refer to the powers of action, emotion, intellect and will.  Each of these aspects of the soul can be used in either a positive or negative way. One can choose to perform good deeds or bad, indulge in positive or negative emotions, or use one’s intellect to accomplish constructive or destructive ends.  Our will can also be directed towards the positive or the negative.  Yechidah, on the other hand, is the essence of the soul, which cannot be corrupted by our surroundings.  The Yechidah is connected to the divine at all times, and always reflects its Creator. 

Over the course of our daily lives, the Yechidah rarely finds expression.  Only when we are confronted with a challenge that threatens to sever our link with G-d, our Yechidah rises up and reveals itself.  The Yechidah cannot, and will not, allow itself to be separated from its divine source.

The teachings of Kabbalah explain that the entire Jewish People is comprised of a single, united soul.  Moshiach is called the “general Yechidah,” containing and reflecting the soul root of every Jew.  Each of our souls is a reflection or ray of this general Yechidah.

When a Jew reveals his penchant for self-sacrifice and overcomes his spiritual challenges, he is revealing the spark of Moshiach within his soul.  This gives each one of us the power to bring the Redemption.  When we arouse the Yechida within us, we release ourselves from the wiles of the evil inclination, which leads to the entire Jewish People being released from the shackles of exile. 

(Yeshaya 52:13. Bereishit Rabba, Chapter 14:9. Devarim Rabba, 2:37. Perush Ramaz on Zohar, Vol. 2, p. 43, Vol. 3, p. 260. Meor Einayim, Parshas Pinchas. Kuntres Inyana shel Toras Hachassidus.