Question:

The Redemption, in essence, will be a spiritual process. Yet we will experience it as souls in bodies. Why?

 
Answer: 

The explanation for why the Redemption will unfold to us as souls in bodies is twofold. Firstly, it is not proper to withhold from the body its rightful reward and pleasure from the Redemption. The Redemption will come as a reward for the mitzvot we performed as a partnership of soul and body. There is no reason why only the soul should reap the benefits without including the body.

The Talmud uses a metaphor of two watchmen, a blind and a lame one, who were appointed to guard the king’s orchard. The lame one, tempted by the luscious figs, persuaded the blind guard to give him a ride on his shoulders so he could pick the fruit, and they would both enjoy them together. When the king discovered the theft, each guard denied involvement: the blind one said he could not see the fruit, and the lame one said he could not reach them. The king ordered the blind man to carry the lame one on his back and he punished them both together.

The analogy applies in this case: Just as the blind and lame watchmen were punished together for their joint crime, the same is true for the reward for mitzvot. Both partners, the soul and the body, deserve to share in the reward.

The Lubavitcher Rebbe explains that moreover, the whole purpose of creation is because G-d desired a "dwelling place in the lower world." In other words, to perfect the physicality of the world so that it is a fitting receptacle for G-d's presence, or, as Chassidism refers to it, "the revelation of the essence of the Infinite, blessed be He." The Redemption represents that revelation. Therefore, it will not come to souls without bodies, since that would defeat the whole purpose. A soul within a body represents a "dwelling" for the Divine.

The purpose of creation is expressed when the physical body is able to contain the G-dly energy in its purest, unconcealed form. Therefore, the Redemption will come to souls within bodies.

Sources: Sanhedrin 91b. Toras Menachem, Menachem Tzion, 390. Igros Kodesh vol. 2, p. 66. Sicha of the Lubavitcher Rebbe, Simchat Torah 5719.