Christ created His own Church about 2000 years ago. Any church that only began to exist 200 years ago is not the Church that Jesus Christ started. Period. I don't have to say it. Christ Himself said it when He said that He build His Church on a rock, and that His Church shall not fall away, like those houses built on sand. Anyone who claims that Christ's own Church, founded by Him on the preaching of His own, chosen Apostles to be a light in the world, fell away, is saying the exact opposite of what Christ Himself clearly preached with regards to His Church. They are liars, plain and simple, unless Christ is a liar. I believe Christ.
If you say that the Body of Christ fell away from its Head, Christ, then you wage war on the Body of Christ. By teaching false things about Who Christ is, and about Who the Father is, and Who the Holy Spirit is, you make yourself an enemy of Christ and His Body.
And the Mormons do not obey Christ's most essential commandment.
His church did fall away as prophesied:
(New Testament | 2 Thessalonians 2:3 - 17)
3 Let no man deceive you by any means: for
that day shall not come, except there come a falling away first, and that
man of sin be revealed, the son of perdition;
4 Who opposeth and exalteth himself above all that is called God, or that is worshipped; so that he as God sitteth in the temple of God, shewing himself that he is God.
5 Remember ye not, that, when I was yet with you, I told you these things?
6 And now ye know what withholdeth that he might be revealed in his time.
7 For the mystery of iniquity doth already work: only he who now letteth will let, until he be taken out of the way.
8 And then shall that Wicked be revealed, whom the Lord shall consume with the spirit of his mouth, and shall destroy with the brightness of his coming:
9 Even him, whose coming is after the working of Satan with all power and signs and lying wonders,
10 And with all deceivableness of unrighteousness in them that perish;
because they received not the love of the truth, that they might be saved.
11 And for this cause God shall send them strong delusion, that they should believe a lie:
12 That they all might be damned
who believed not the truth, but had pleasure in unrighteousness.
13 But we are bound to give thanks alway to God for you, brethren beloved of the Lord, because God hath from the beginning chosen you to salvation through sanctification of the Spirit and belief of the truth:
14 Whereunto he called you by our gospel, to the obtaining of the glory of our Lord Jesus Christ.
15 Therefore, brethren, stand fast, and
hold the traditions which ye have been taught, whether by word, or our epistle.
16 Now our Lord Jesus Christ himself, and God, even our Father, which hath loved us, and hath given us everlasting consolation and good hope through grace,
17 Comfort your hearts, and
stablish you in every good word and work.
The man of sin is Satan.