Matthew 7: (see also Mark 1:22)
28 And it came to pass, when Jesus had ended these sayings, the people were astonished at his doctrine:
29 For he taught them as one having authority, and not as the scribes.
Matt 21
23 ¶ And when he was come into the temple, the chief priests and the elders of the people came unto him as he was teaching, and said, By what authority doest thou these things? and who gave thee this authority?
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27 And they answered Jesus, and said, We cannot tell. And he said unto them, Neither tell I you by what authority I do these things. (see also Mark 11 & Luke 20)
Mark 1:
25 And Jesus rebuked him, saying, Hold thy peace, and come out of him.
26 And when the unclean spirit had torn him, and cried with a loud voice, he came out of him.
27 And they were all amazed, insomuch that they questioned among themselves, saying, What thing is this? what new doctrine is this? for with authority commandeth he even the unclean spirits, and they do obey him. (see also Luke 4)
Luke 9:
1 Then he called his twelve disciples together, and gave them power and authority over all devils, and to cure diseases.
2 And he sent them to preach the kingdom of God, and to heal the sick.
Luke 19:
17 And he said unto him, Well, thou good servant: because thou hast been faithful in a very little, have thou authority over ten cities.
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26 For I say unto you, That unto every one which hath shall be given; and from him that hath not, even that he hath shall be taken away from him. (they didn't use their talent/authority to bless others aka. make an increase)
Luke 22: (This scripture below is FIRE about Authority!!)
24 ¶ And there was also a strife among them, which of them should be accounted the greatest.
25 And he said unto them, The kings of the Gentiles exercise lordship over them; and they that exercise authority upon them are called benefactors.
26 But ye shall not be so: but he that is greatest among you, let him be as the younger; and he that is chief, as he that doth serve.
27 For whether is greater, he that sitteth at meat, or he that serveth? is not he that sitteth at meat? but I am among you as he that serveth.
2 Corinthians 10:
7 Do ye look on things after the outward appearance? If any man trust to himself that he is Christ’s, let him of himself think this again, that, as he is Christ’s, even so are we Christ’s.
8 For though I should boast somewhat more of our authority, *which the Lord hath given us for edification*, and not for your destruction, I should not be ashamed:
Rev. 13
2 And the beast which I saw was like unto a leopard, and his feet were as the feet of a bear, and his mouth as the mouth of a lion: and the dragon gave him his power, and his seat, and great authority.
1 Nephi 10:
22 And the Holy Ghost giveth authority that I should speak these things, and deny them not.
Words of Mormon 1:
17 For behold, king Benjamin was a holy man, and he did reign over his people in righteousness; and there were many holy men in the land, and they did speak the word of God with power and with authority; and they did use much sharpness because of the stiffneckedness of the people—
Mosiah 13:
5 Now it came to pass after Abinadi had spoken these words that the people of king Noah durst not lay their hands on him, for the Spirit of the Lord was upon him; and his face shone with exceeding luster, even as Moses’ did while in the mount of Sinai, while speaking with the Lord.
6 And he spake with power and authority from God; and he continued his words, saying:
Mosiah 18:
13 And when he had said these words, the Spirit of the Lord was upon him, and he said: Helam, I baptize thee, having authority from the Almighty God, ...
17 And they were called the church of God, or the church of Christ, from that time forward. And it came to pass that whosoever was baptized by the power and authority of God was added to his church.
18 And it came to pass that Alma, having authority from God, ordained priests; even one priest to every fifty of their number did he ordain to preach unto them, and to teach them concerning the things pertaining to the kingdom of God.
...
26 **And the priests were not to depend upon the people for their support; but for their labor they were to receive the grace of God, that they might wax strong in the Spirit, having the knowledge of God, that they might teach with power and authority from God.**
Mosiah 21:
33 And it came to pass that king Limhi and many of his people were desirous to be baptized; but there was none in the land that had authority from God. And Ammon declined doing this thing, considering himself an unworthy servant.
34 Therefore they did not at that time form themselves into a church, waiting upon the Spirit of the Lord.
Mosiah 23:
16 And now, Alma was their high priest, he being the founder of their church.
17 And it came to pass that none received authority to preach or to teach except it were by him from God. Therefore he consecrated all their priests and all their teachers; and none were consecrated except they were just men.
18 Therefore they did watch over their people, and did nourish them with things pertaining to righteousness.
Mosiah 27:
14...for this purpose have I come to convince thee of the power and authority of God, that the prayers of his servants might be answered according to their faith.
15 And now behold, can ye dispute the power of God? For behold, doth not my voice shake the earth? And can ye not also behold me before you? And I am sent from God.
Alma 5:
3 I, Alma, having been consecrated by my father, Alma, to be a high priest over the church of God, he having power and authority from God to do these things, behold, I say unto you that he began to establish a church in the land which was in the borders of Nephi; yea, the land which was called the land of Mormon; yea, and he did baptize his brethren in the waters of Mormon.
Alma 17 :
3 But this is not all; they had given themselves to much prayer, and fasting; therefore they had the spirit of prophecy, and the spirit of revelation, and when they taught, they taught with power and authority of God.
Helaman 5:
18 And it came to pass that Nephi and Lehi did preach unto the Lamanites 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 6:
5 Yea, and many did preach with exceedingly great power and authority, unto the bringing down many of them into the depths of humility, to be the humble followers of God and the Lamb.
Helaman 11:
18 And behold, the people did rejoice and glorify God, and the whole face of the land was filled with rejoicing; and they did no more seek to destroy Nephi, but they did esteem him as a great prophet, and a man of God, having great power and authority given unto him from God.
3 Nephi 7:
17 And he did minister many things unto them; and all of them cannot be written, and a part of them would not suffice, therefore they are not written in this book. And Nephi did minister with power and with great authority.
3 Nephi 11:
21 And the Lord said unto him: I give unto you power that ye shall baptize this people when I am again ascended into heaven.
...
24 And now behold, these are the words which ye shall say, calling them by name, saying:
25 Having authority given me of Jesus Christ, I baptize you in the name of the Father, and of the Son, and of the Holy Ghost. Amen.
3 Nephi 12:
1 ...Blessed are ye if ye shall give heed unto the words of these twelve whom I have chosen from among you to minister unto you, and to be your servants; and unto them I have given power that they may baptize you with water; and after that ye are baptized with water, behold, I will baptize you with fire and with the Holy Ghost; therefore blessed are ye if ye shall believe in me and be baptized, after that ye have seen me and know that I am.
Moroni 8:
16 Wo be unto them that shall pervert the ways of the Lord after this manner, for they shall perish except they repent. Behold, I speak with boldness, having authority from God; and I fear not what man can do; for perfect love casteth out all fear.
...
28 Pray for them, my son, that repentance may come unto them. But behold, I fear lest the Spirit hath ceased striving with them; and in this part of the land they are also seeking to put down all power and authority which cometh from God; and they are denying the Holy Ghost.
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Authority has been pounded into our heads by the LDS church our entire lives. When I first told others of my doubts about the church they mused, "where will you go?" because we are taught that the church is the only one who has the authority. This highlights our great mis-understanding of what authority is. When Jesus taught that His flesh was meat indeed and his blood must be consumed - many of his disciples left in dismay and no longer walked with Him. Seeing this Jesus asked His friends and Apostles, "Will ye also go away?" Peter responds (Ruth translation here), "Lord! Where in the world would we even go?? You have the words of eternal life. We believe You and we know that You are the Holy One of God!!"
If you want to know who has the Authority - it's Jesus and the Father. They have it.
If you want to know if you have the Authority to act in their name - you must ask Them.
If you know you don't have it but you want it - then you must ask Them that too.
D&C 88: