One missionary used to use this scripture in his door approach. When he was rejected by someone who said that they were already Christian, he would ask if they believed in Christ. They would answer, “yes”, then he would open his Book of Mormon and read 2 Nephi 33:10. He would say, “If you believe in Christ, you will believe in this book. It is another testament of Jesus Christ and I have been sent to bring it to you.” I don’t know if this bold approach was successful or not, but it was certainly doctrinally accurate. If any Christian in the world really believes in Jesus Christ and has a sincere desire to follow him, they will feel of the spirit of the Book of Mormon. They will recognize that the words of Nephi are the words of Christ, and they will have no choice but to accept the truth or have it stand as a witness against them at the last day.
“The Book of Mormon is the most Christ-centered scriptural record ever published. Every doctrine within its covers is but an appendage to as central theme- the testimony that Jesus is the Christ. All who believe in Christ will believe the words of this book. One cannot truly believe in the Bible and at the same time not believe in the Book of Mormon. ’There is not that person on the face of the earth,’ Brigham Young said, ’who has had the privilege of learning the Gospel of Jesus Christ from these two books [the Bible and the Book of Mormon], that can say that one is true, and the other is false. No Latter-day Saint, no man or woman, can say the Book of Mormon is true, and at the same time say that the Bible is untrue. If one be true, both are; and if one be false, both are false.’ (JD 1:38.) To believe the words of one is to believe the words of both (see Mormon 7:9).” (McConkie and Millet, Doctrinal Commentary on the Book of Mormon, vol. 1, p. 375)
Elder Hartmann Rector Jr. tells his conversion story in the book, No More Strangers. He was a minister at the time he read the Book of Mormon and explains the great impact that the words of 2 Nephi 33 had upon his thinking at this important time:
"[Nephi] said: ’And if ye shall believe in Christ ye will believe in these words, for they are the words of Christ, and he hath given them unto me; and they teach all men that they should do good.’
"And that is true; that is what these words do. You can’t argue that they teach anything bad. Nevertheless, to say that they‘re the words of Christ and ’he gave them to me’ is the most daring, dangerous, damning kind of a thing to say if it’s not true. You just don’t serve the cause of Christ in the world by writing fictions about Jesus Christ. I couldn’t believe that any honest, responsible group or church or people would put a thing like this across on the world while trying honestly to serve Jesus Christ.
"In the next verse the writer of those words goes on to indicate that he understands exactly how serious it is. He says: ’And if they are not the words of Christ, judge ye-for Christ will show unto you, with power and great glory, that they are his words, at the last day; and you and I shall stand face to face before his bar; and ye shall know that I have been commanded of him to write these things, notwithstanding my weakness.’
“That is about the strongest thing I’d ever read in my life, because I knew there was going to be a ”last day" before I ever heard of this Book of Mormon. But then in the next verse the writer said the most touching thing I’d ever read: ’And I pray the Father in the name of Christ that many of us, if not all, may be saved in his kingdom at the great and last day.’ (2 Nephi 33:10-11.)
"That struck me as wonderful! I thought: ‘What’s wrong with that? That’s absolutely right. He doesn‘t want me to join any ’Mormon’ Church-no mention of it. Just entrance into the Father’s kingdom by believing in Jesus Christ! If that isn‘t true the Bible’s not true either, because that’s all that the Bible is about.’ And yet, if what I had now read was true, why in heaven‘s name hadn’t we heard about it before? I just didn’t know what to make of it!
"…So I just put my doubts on the shelf as fast as they came to mind and tried to deal with what the book seemed to say. By the time I had finished reading the book I was really in turmoil about the whole thing. If it were true, I couldn’t understand why all this had been kept from the world in general for so long. Yet, if it wasn’t true, I didn’t know what I believed. I knew that if I went to any of my colleagues in the ministry for counsel, with the best of intentions they could only say one thing…
"…The next day [after a meeting with the missionaries] I went into the little chapel next door to our house, took the Bible and Book of Mormon with me, closed the door, and went up front and knelt down. Then I poured it all out to the Lord-everything that was churning inside me about the mess that I was in now, for I knew what would happen if I went ahead and was baptized. I knew it would be the end of my ministry, but I could take that. I was afraid, however, that it might also be the end of my marriage, for my wife was already extremely upset about what I’d been doing all week long…I also worried about my friends, my fellow colleagues in the ministry, and the people who believed in me….
"I poured all this out to the Lord. Then I left it with him and went back and sat down to try to think through things again. I opened up the Book of Mormon and reread the things I had underlined the first time through it to see if they still impressed me now as they did then. They did. I concluded that this book had to be true even though I couldn‘t explain where it came from and why we hadn’t had it before. But then fear would just sweep me off my feet again…
"Round and round it went like that all day long from about 7:00 A.M. until toward 6:00 P.M. Then suddenly I realized what was happening. Here I was asking God for the answers and was being turned to the scriptures. Comparing the Book of Mormon with the Bible, I concluded that it had to be true even though I couldn’t explain it. Then just when I was ready to move out in faith, fear and doubt would sweep over me again and block everything. Finally it dawned upon me that my fears and doubts were not coming from God in answer to my prayers, so I knew where they were coming from.
“I put the two books together, walked back over to the elders’ quarters and knocked on the door again. This time I said to the elder who opened the door, ‘I’m ready now. I’ve got a lot of fears yet, but no more doubts.’ He invited me in and they all gathered around. One of them had a big grin on his face as he said, ‘We’ve been having a great spirit here, fasting and praying for you all day.‘ Of course I didn’t know they did that kind of thing and they didn’t know what I was doing. But God knew, and together we won.” (Hartmann and Connie Rector, No More Strangers, pp. 50-56)