And [God] said, “Do not draw near here. Take your shoes off your feet, because the place upon which you stand is holy soil. (Exodus 3:5)
There are a variety of reasons why shoes are removed at specific times or on certain festivals. On Yom Kippur (the Day of Atonement) we refrain from wearing leather shoes.
When Adam and Eve ate from the tree of knowledge of good and evil, one of their punishments was that God cursed the ground (Genesis 3:17). Consequently, under normal circumstances we wear shoes which separate us from the ground. Through the holiness of Yom Kippurthe ground once again becomes sanctified and we return to a state of holiness similar that prior to Adam’s sin (Taamei HaMinhagim 741:7). This also explains the need for Moshe (Moses) to remove his shoes as he approached the burning bush (Midrash Rabbah Shemos 2:6).
The Shulchan Aruch (Code of Jewish Law) states that when the kohanim (priests) ascend the platform in front of the ark to bless the community they must also remove their shoes (Orach Chaim 128:5). In this instance, the reason seems to stem from practical concerns rather than spiritual motives (Mishnah Berurah 128:15).
Normally when one buys a new item of clothing of significant value, the special blessing of shehechiyanu is recited (see Chief Rabbi’s siddur page 780) and there is a tradition for others to say תבלה ותתחדשtevalah v’titchadeish (lit. ‘wear out and renew’). Rabbi Moshe Isserlis (d. 1572) excludes shoes from this custom on the grounds that an animal had to die to produce the leather to make the shoes (Orach Chaim 223:6). The same is true for a new set of tefilin.
The removal of shoes is also a sign of mourning (Isaiah 20:2). Those who have lost close relatives refrain from wearing leather shoes for the shiva period. Similarly, we are prohibited from wearing leather shoes on Tisha B’Av when we mourn the loss of both Temples in Jerusalem (Orach Chaim 554:1).
From this we see that the deep spiritual significance of wearing shoes or removing them carries a wide ranging influence on our laws and customs.