If the Church Is Built upon My Gospel Then Will the Father Show Forth His Own Works in It

God’s power is the only non-entropic force in the universe. Every organization that does not keep His authority and His gospel tightly at its center will come to naught in the end. In the verses below, Jesus teaches this principle (in the context of church organization) to His disciples in the Americas:  

“…If it so be that the church is built upon my gospel then will the Father show forth his own works in it. But if be not built upon my gospel, and is built upon the works of men, or upon the works of the devil, verily I say unto you they shall have joy in their works for a season, and by and by the end cometh, and they are hewn down and cast into the fire, from whence there is no return. For their works do follow them, for it is because of their works that they are hewn down; therefore remember the things that I have told you.” (3 Nephi 27:10-12)

Questions:

-Is the search for God the search for things that last forever?

-Does it make sense to stop that search at any point and resign oneself to the temporal and fleeting?

-Is there a church on the Earth that has the authority from God to seal loving and committed family relationships as eternal relationships?

Great Power and Authority to Preach Only Comes if Given by God

The brother missionaries, Nephi and Lehi, had miraculous results when preaching the word of God because they had authority from God to preach and then spoke the words that God gave them through the Holy Spirit.

…They did preach with great power, insomuch that they did confound many…dissenters…insomuch that [the dissenters] came forth and did confess their sins and were baptized unto repentance…And…Nephi and Lehi did preach…with such great power and authority, for they had power and authority given unto them that they might speak, and they also had what they should speak given unto them. (Helaman 5:17-18)

Questions:

-Who has a line of priesthood authority to preach that goes directly back to Jesus Christ?

-How does one rely on the Holy Spirit so that the words spoken, when preaching, are given by God?