Mosiah 17:11 - 17:15

Mosiah 17:11 And now king Noah was about to release him, for he feared his word; for he feared that the judgments of God would come upon him.

That shook up king Noah and he was about to release Abinadi because he was fearful that he would be held accountable by the Lord if he did execute him.

Mosiah 17:12 But the priests lifted up their voices against him, and began to accuse him, saying: He has reviled the king. Therefore the king was stirred up in anger against him, and he delivered him up that he might be slain.

However the remaining priests (Alma was gone) protested to the king that Abinadi had prophesied against the kings person and that could not be allowed to stand.
[That would weaken his position as a leader of the people. They would be looking to Abinadi for leadership as he would be known as a prophet and they were generally listened to more than any king.]

Mosiah 17:13 And it came to pass that they took him and bound him, and scourged his skin with faggots, yea, even unto death.

Before burning him at the stake, they beat him with faggots until he was almost dead.

Mosiah 17:14 And now when the flames began to scorch him, he cried unto them, saying:

As the flames were being to burn his skin, he gives a prophecy to his executioners.

Mosiah 17:15 Behold, even as ye have done unto me, so shall it come to pass that thy seed shall cause that many shall suffer the pains that I do suffer, even the pains of death by fire; and this because they believe in the salvation of the Lord their God.

Abinadi says that the king and the priest will and their relatives will continue to persecute the righteous among the people and burning them by fire to as they are doing to Abinadi. All because they believe in the gospel of Christ.
[Again believing in Christ is a threat to the establishment. Loyalty to the Gospel means the people will not be loyal to their political leaders. The political leaders will feel threatened by this and in order to maintain their power, as they see it, they will either have to forbid them practicing Christianity or kill them.]