Which church is true?

Only one true church?

According to teachings by Joseph Smith and a Book of Mormon prophet called Nephi, The Church of Jesus Christ of Latter-day Saints is the only true church of Jesus Christ on the earth today.  All the other churches (and one may include all other religions) are classified as the "church of the devil."

Doctrine and Covenants 115:4 says, "For thus shall my church be called in the last days, even The Church of Jesus Christ of Latter-day Saints."

When you dig deeper into LDS theology, you actually discover that they teach about three main churches.  More about this later below.

Doctrine and Covenants 1:30 says, "And also those to whom these commandments were given, might have power to lay the foundation of this church, and to bring it forth out of obscurity and out of darkness, the only true and living church upon the face of the whole earth, with which I, the Lord, am well pleased, speaking unto the church collectively and not individually."

This would fall in line with a teaching by 1 Nephi (14:10) - "And he said unto me: Behold there are save two churches only; the one is the church of the Lamb of God, and the other is the church of the devil; wherefore, whoso belongeth not to the church of the Lamb of God belongeth to that great church, which is the mother of abominations; and she is the whore of all the earth."

Joseph Smith taught that the house for the work of the Presidency (and one may assume Mormon Temples too) were not to have any unclean thing (sinful being) enter therein.   For if any unclean thing did so, the glory of God and His presence would not come into it (Doctrine and Covenants 94:9)

According to the Bible, salvation is not found through membership in a certain church or religion.  Jesus is the way, the truth, and the life.  No one comes to the Father except through Him.  Jesus is the door to eternal life.

Do present day Mormons agree with what their church teaches?

It would appear that some Mormons agree with what their church teaches while other members do not.

"But so far as the Latter-day Saints are concerned, the majority of them will not turn from the faith of their fathers" (Joseph 
Fielding Smith, Doctrines of Salvation, volume 1, page 244). 

"We are laboring in the direction of eternal life and progression. There is no variance among the teachers in Israel concerning 
the principles of the gospel. We are united concerning these things. There is no division among the authorities, and there 
need be no division among the the people" (ibid, pages 245-246).

But when we carefully examine Mormon teachings, we find there is some great division - even among Presidents of the 
LDS Church both past and present.

Was the original church restored in the form of the LDS Church?

According to a Mormon booklet called, "The Restoration of the Gospel of Jesus Christ," The Church of Jesus Christ of Latter-day Saints is said to be a restored church and not a reformation movement. In the definition statement, it writes, "Restoration differs from reformation in that to reform means to modify an existing organization or practice in an effort to return it to its original state, while to restore means to reestablish or renew the original organization or practice in its entirety" (p. 19).

When you study the original church in the Bible as it was growing, you will see a mention of 12 Apostles. But when you read a sermon called "Looking Back and Moving Forward" (178th General Conference held in April 2008, local copy), it writes, "On Saturday, February 2, 2008, funeral services for President Hinckley were held in this magnificent Conference Center - a building which will ever stand as a monument to his foresight and vision. During the funeral, beautiful and loving tributes were paid to this man of God. The following day, all 14 ordained Apostles living on the earth assembled in an upper room of the Salt Lake Temple."

Did you notice that?  On February 2 there were 14 living Apostles. When Mr. Hinckley was alive he was another living Apostle, thus making a total of 15.

This is a clear example showing that The Church of Jesus Christ of Latter-day Saints is not a restored church of the original. You may even want to look into the Book of Mormon. There is no mention of there being more than 12 Apostles. Also, there is no office of the Seventy in the church that Jesus is said to have established somewhere in the Americas according to those believe in the Book of Mormon.

There is some thinking that Apostles were very special witnesses of Christ who had physically seen Him and that when they died, no others were chosen as replacements.

One thing that Latter-day Saints have in common with Roman Catholics is that they believe Peter is the head of the church based on him receiving the keys to bind and loose in Matthew 16:19. What they fail to realize is that all the disciples received the keys of binding and loosing - see Matthew 18:1-3,18.

This is a common error by some religious groups - but not one that you would expect from someone who does a careful study of the Bible.

Oddly enough, the keys of binding and loosing are not even mentioned in the churches of the Book of Mormon.

3 main churches in LDS theology?

When you dig deeper into LDS theology, you actually discover 3 main churches.

The first (general) church is, as was discussed above, called The Church of Jesus Christ of Latter-day Saints.

The second church is the church of the devil (1 Nephi 14:10).

The third church is called "the church of the Firstborn." The LDS Church believes that this other church is made up of the gods and goddesses who dwell in the presence of the Mormon Heavenly Father as kings, queens, priests and priestesses (Doctrine and Covenants 76:54,56,62,66,71). Mormons who do not reach exaltation will not be a part of this church.

Brigham Young University has a more in-depth study about this in the Encyclopedia of Mormonism:

http://eom.byu.edu/index.php/Church_of_the_Firstborn 
Author: Barrett, Ivan J.
(local copy)

The Church of the Firstborn is Christ's heavenly church, and its
members are exalted beings who gain an inheritance in the highest
heaven of the celestial world and for whom the family continues
in eternity.

In the scriptures Jesus Christ is called the Firstborn. He was
the first spirit child born of God the Father in the premortal
existence and was in the beginning with God (John 1:1-5, 14).
Christ also became the Firstborn from the dead, the first person
resurrected, "that in all things he might have the preeminence"
(Col. 1:18; Acts 26:23; 1 Cor. 15:23; Rev. 1:5). Even as the
first principles and ordinances, including baptism in water and
the reception of the Holy Ghost, constitute the gate into the
earthly Church of Jesus Christ, so higher ordinances of the
priesthood constitute the gate into the Church of the Firstborn.
To secure the blessings that pertain to the Church of the
Firstborn, one must obey the gospel from the heart, receive all
of the ordinances that pertain to the house of the Lord, and be
sealed by the Holy Spirit of promise in the Celestial Kingdom of
God (D&C 76:67, 71, 94;77:11;78:21;88:1-5; TPJS, p. 237).

Revelations to the Prophet Joseph Smith supplement those of the
New Testament to indicate that the Church of the Firstborn
consists of those who have the inheritance of the Firstborn and
become joint-heirs with Christ in receiving all that the Father
has (Rom. 8:14-17; D&C 84:33-38; see Heirs: Heirs of God). The
Lord said, "If you keep my commandments you shall receive of his
fulness, and be glorified in me as I am in the Father; …I…am the
Firstborn; …And all those who are begotten through me are
partakers of the glory of the same, and are the Church of the
Firstborn" (D&C 93:20-22). The Church of the Firstborn is the
divine patriarchal order in its eternal form. Building the
priesthood family order on this earth by receiving sealings in
the temple is a preparation and foundation for this blessing in
eternity (see Gospel of Abraham).

When persons have proved themselves faithful in all things
required by the Lord, it is their privilege to receive covenants
and obligations that will enable them to be heirs of God as
members of the Church of the Firstborn. They are "sealed by the
Holy Spirit of promise" and are those "into whose hands the
Father has given all things" (D&C 76:51-55). They will be priests
and priestesses, kings and queens, receiving the Father's glory,
having the fulness of knowledge, wisdom, power, and dominion (D&C
76:56-62; cf. 107:19). At the second coming of Jesus Christ, the
"general assembly of the Church of the Firstborn" will descend
with him (Heb. 12:22-23; JST Gen. 9:23; D&C 76:54, 63).