When it comes to a marriage relationship, the only real interest of the two people involved is whether or not they are strongly bonded and attached to each other. The same is true when it comes to HaKadosh Baruch Hu, Klal Yisrael, and the purpose of the Mishkan. The Mishkan was not simply a building. It was a place for Hashem to rest His Presence, Shechinah. As the pasuk (Shemos 25:8) says, “V’asu li mikdash v’shachanti b’socham, make a Sanctuary for Me so that I can dwell within it.”
The purpose of the Mishkan is for Bnei Yisrael to feel Hashem’s closeness. Entering the Mishkan one would immediately feel close to Hashem. One would instantaneously sense the presence of our Creator. One would powerfully recall the marriage of Klal Yisrael to Hashem Yisbarach.
This being the case, every minute detail needed to be constructed only for the sake of the relationship with Hashem, l’Shmi. Insincere and selfish reasons for donating would have been severely inappropriate and were not to be accepted.
This marriage relationship with Hashem, and the attachment to Him that we are supped to have, is the purpose of korbanos, sacrifices, as well. The Rambam (Hilchos Beis HaBechira 1:1) writes that the purpose of building the Beis HaMikdash is so that we have a place to offer korbanos to Hashem. Many have pointed out that the word korban is derived from the word karov, which means closeness. Bringing korbanos to Hashem is designed to allow us to feel close to Him. We build the House of Hashem so that we can allow Him to rest His Presence among us and, once He does so, we respond by offering Him our korbanos.
We need to ask ourselves often, “Ayeh Hashem/Where is G-d” in our lives. What can we do to make more of a connection with G-d in our lives? This is what will transform Tisha B’Av into a holiday.