"... I've learned that the Lord ... has only called us to pursue Him in spirit ..."
In Genesis 16 Abraham worked hard to try to fulfill God's promise according to his own concept and his own efforts. This resulted in the birth of Ishmael, whom God disregarded. In the same way that God made His promise with Abram clear, He has made His desire for the Church clear through His word and through the operation of His Holy Spirit.
Just as Abram listened to Sarai instead of consulting the Lord, we're often far too willing to pursue the Lord through natural concepts and our own ideas rather than according to the leading of the Holy Spirit. If what we do is not strictly according to the Lord's heart's desire and according to the pure revelation in the word, our efforts are in vain.
I've learned that the Lord has not called me to go out into the world and exert great effort for Him. He doesn't want me to worship Him in a "religious" way, according to the traditions of man or according to my preferences. He has only called us to pursue Him in spirit through prayer, the word, and fellowship with His Body. Anything I do that isn't according to His leading is just another Ishmael to Him.