Is God a liar? Can man corrupt something God declares will not pass away?
“And I say also unto thee, That thou art Peter, and upon this rock I will build my church; and the gates of hell shall not prevail against it.” Matt 16:18
“Ye have not chosen me, but I have chosen you, and ordained you, that ye should go and bring forth fruit, and that your fruit should remain: that whatsoever ye shall ask of the Father in my name, he may give it you.” John 15:16
“And in the days of these kings shall the God of heaven set up a kingdom, which shall never be destroyed: and the kingdom shall not be left to other people, but it shall break in pieces and consume all these kingdoms, and it shall stand for ever.” Daniel 2:44
This last scripture was made before the New Testament, not after Joseph Smith "restored" the Church. The real New Testament Church of Christ with the original Apostles, teachers, evangelists, and so forth. That is the one that will stand forever.