The preaching of Abinadi, the prophet was a blessing to many. He gave his life for his testimony of Jesus Christ, and it was not in vain. Through Alma, many hearts were changed as they heard the words of the prophet.
The people who came looking for Alma to hear his preaching were filled with grace when they were baptized. One of the aspects of the grace of God is the enabling power of the atonement.
Mosiah 18:16 "And after this manner he did baptize every one that went forth to the place of Mormon; and they were in number about two hundred and four souls; yea, and they were baptized in the waters of Mormon, and were filled with the grace of God."
In my opinion, the grace of God gave them power to come together and support one another.
Mosiah 18:21 "And he commanded them that there should be no contention one with another, but that they should look forward with one eye, having one faith and one baptism, having their hearts knit together in unity and in love one towards another. "
In the coming chapters of the Book of Mormon, the bond of love they have for God and for each other, will give them power to endure the hardship of the bondage imposed on them by the wicked priests of Noah and the Lamanites they influence.
The people of Limhi, on the other hand, also desired to be free from bondage but grace, or the enabling power of the atonement, was granted slowly, only as they opened their hearts.
Mosiah 21:15 "And now the Lord was slow to hear their cry because of their iniquities; nevertheless the Lord did hear their cries, and began to soften the hearts of the Lamanites that they began to ease their burdens; yet the Lord did not see fit to deliver them out of bondage."
King Limhi commanded them to see to each other's welfare. This gave them a closer bond to each other.
Mosiah 21:17 "Now there was a great number of women, more than there was of men; therefore king Limhi commanded that every man should impart to the support of the widows and their children, that they might not perish with hunger; and this they did because of the greatness of their number that had been slain."
The grace of God was working in behalf of these people aligned to King Limhi. They were prepared for Ammon and when he arrived they rejoiced in the knowledge of the people of Zarahemla and also in the knowledge of the gospel of Jesus Christ.
Mosiah 21:32 "And now since the coming of Ammon, king Limhi had also entered into a covenant with God, and also many of his people, to serve him and keep his commandments. And it came to pass that king Limhi and many of his people were desirous to be baptized; "
And thus we see that the power of at-one-ment works through preaching the gospel of Jesus Christ. Once the spirit can enter into the hearts of a man or a woman, an inward change brings desire be aligned with God and a desire to be connected to others.