2 Nephi 10

As Jacob continues his teachings on the words of Isaiah, he returns to the vision of his brother wherein an angel said -

"...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." (Book of Mormon | 1 Nephi 14:10)

Jacob then explains what the angel meant by these "two churches" -

"Wherefore, he that fighteth against Zion, both Jew and Gentile, both bond and free, both male and female, shall perish; for they are they who are the whore of all the earth; for they who are not for me are against me, saith our God." (Book of Mormon | 2 Nephi 10:16)

Therefore -

"...cheer up your hearts, and remember that ye are free to act for yourselves—to choose the way of everlasting death or the way of eternal life." (Book of Mormon | 2 Nephi 10:23)

It is our choice whether we fight against Zion or not. We learn of those Jews that chose to fight against Zion for personal gain, or -

"...among those who are the more wicked part of the world; and they shall crucify him—for thus it behooveth our God, and there is none other nation on earth that would crucify their God.
4 For should the mighty miracles be wrought among other nations they would repent, and know that he be their God.
5 But because of priestcrafts and iniquities, they at Jerusalem will stiffen their necks against him, that he be crucified." (Book of Mormon | 2 Nephi 10:3 - 5)

For -

"...priestcrafts are that men preach and set themselves up for a light unto the world, that they may get gain and praise of the world; but they seek not the welfare of Zion." (Book of Mormon | 2 Nephi 26:29)

In other words, they fight against Zion. To be for the Lamb of God, we must -

"...reconcile yourselves to the will of God, and not to the will of the devil and the flesh; and remember, after ye are reconciled unto God, that it is only in and through the grace of God that ye are saved." (Book of Mormon | 2 Nephi 10:24)