3 Nephi 2:2

Imagining up some vain thing in their hearts, that it was wrought by men and by the power of the devil, to lead away and deceive the hearts of the people; and thus did Satan get possession of the hearts of the people again, insomuch that he did blind their eyes and lead them away to believe that the doctrine of Christ was a foolish and a vain thing.

Deception turns the truth upside down. Satan would have us believe that the truth is a deception, and that his deception is the truth. He is not so much interested in getting us to believe his bold-faced lies  as he is in getting us to simply question God's truth and relinquish our commitment to it.

3 Nephi 1:22

And it came to pass that from this time forth there began to be lyings sent forth among the people, by Satan, to harden their hearts, to the intent that they might not believe in those signs and wonders which they had seen; but notwithstanding these lyings and deceivings the more part of the people did believe, and were converted unto the Lord.

The sign of a night without darkness at the Savior's birth was dramatic enough to get people's attention so they would listen to the message of the gospel and the Messiah. Many were converted, or at least they joined the church. But conversion cannot be dependent on a sign. Just a few years later, this skin-deep conversion would slip away for many, and the people for the most part would return to apostasy. There are many ways to plant the seed of faith in people's hearts, but the seed must be nurtured and carefully cultivated, or it will not bear fruit.

3 Nephi 1:8

But behold, they did watch steadfastly for that day and that night and that day which should be as one day as if there were no night, that they might know that their faith had not been vain.

The righteous believers did not need a sign to ignite their faith, but they needed the promised sign to confirm their faith. It is okay to ask for confirmation. That is not sign-seeking. It is like asking for a testimony of the Book of Mormon as you read it. It is not weakness to ask for validation of your faith as you exercise it. God wants us to ask, and he promises us marvelous answers.

Helaman 16:23

I Choose to Believe - Phillips, Craig and Dean

And notwithstanding the signs and the wonders which were wrought among the people of the Lord, and the many miracles which they did, Satan did get great hold upon the hearts of the people upon all the face of the land.

I repeat: we choose what we believe. It is as easy to believe in God as to believe in Satan, or evolution, or humanism, or shamanism, or atheism, or any other -ism. We can find "proof" for whatever we choose to believe. But ultimately only one truth exists independent and outside of all tangible evidence. Those who witness that truth know the difference between reality and everything else. We can accept their testimony and put it to the test. God is no respecter of persons, and if we do as his witnesses have done before us, we can have the same witness. Nevertheless, it always begins with our choice.

Helaman 16:20

But behold, we know that this is a wicked tradition, which has been handed down unto us by our fathers, to cause us that we should believe in some great and marvelous thing which should come to pass, but not among us, but in a land which is far distant, a land which we know not; therefore they can keep us in ignorance, for we cannot witness with our own eyes that they are true.

Physical proof is always demanded by those who refuse faith. The thing is, when they get the proof they demand, they do not accept it. Signs, wonders, and miracles are happening all around these people, and they dismiss the prophecies as lucky guesses. This is a lesson for us to learn about the Book of Mormon. Many people claim they would believe the Book of Mormon if they could only see the gold plates. But the reality is that they would only try to prove that the plates are a fraud. We first choose to believe, and then we are strengthened by evidence. Evidence never produces faith. It may catch our attention, but sooner or later we must make a conscious choice regardless of the evidence.

Helaman 16:6

But the more part of them did not believe in the words of Samuel; therefore when they saw that they could not hit him with their stones and their arrows, they cried unto their captains, saying: Take this fellow and bind him, for behold he hath a devil; and because of the power of the devil which is in him we cannot hit him with our stones and our arrows; therefore take him and bind him, and away with him.

Isn't it interesting that the unbelievers were willing to ascribe Samuel's miraculous protection to the power of the devil rather than believe it came from God. Apparently any ridiculous belief is better than the truth when the truth involves God. Today people would rather believe in the random chance of evolution than to admit an Intelligence in their own creation.

Helaman 15:7

And behold, ye do know of yourselves, for ye have witnessed it, that as many of them as are brought to the knowledge of the truth, and to know of the wicked and abominable traditions of their fathers, and are led to believe the holy scriptures, yea, the prophecies of the holy prophets, which are written, which leadeth them to faith on the Lord, and unto repentance, which faith and repentance bringeth a change of heart unto them.

Note the sequence of events in this verse. We do not change our hearts and then repent. We repent first, and then our hearts are changed for us by God .