Just as Zionism can be viewed as a return to the Bible which stresses the significance of the land of Israel, the return to spirituality is also a return to the world of Bible where the focus is on the spiritual and experiential. The Bible stresses the direct connection to G-d through Prophecy, the Beit Hamikdash, prayer and the song.
However, if indeed spiritually is so deep rooted in Judaism, this begs the question, why for such a long period have these sides of Judaism been so much less prominent?
One approach is that spirituality is a powerful force and thus dangerous and easily corrupted. In our parsha, the sons of Aaron die when they approach the Holy without the proper preparations. Rav Kook teaches that the sins of the first Temple times - murder, immorality and idolatry, derive a perversion of spirituality. After the destruction of the first Temple, Judaism began to focus on the study of Torah and meticulous fulfillment of the Halacha as this will give us the discipline to one day return to spirituality and allow it to bring to sanctity and not corrupt.