If a conviction of truth comes only through reading the Bible, one can't help but wonder why there are so many different Protestant and Catholic churches in the world today.
The Bible teaches that one cannot know that Jesus is the Lord without the Holy Ghost (1 Cor. 12:3), which works on the heart and guides us into all truth (John 16:13). For example, on the day of Pentecost, the three thousand who were led to Jesus, and who joined the Church and were baptized were not converted by reading the New Testament--it hadn't been written yet. They weren't converted by studying the writing of the ancient prophets either the Pharisees and Sadducees had been doing that for centuries, yet they didn't accept Christ.
The three thousand were converted because of a pouring out of the Spirit, which bore testimony to them. They were, as the Bible so aptly states, "pricked in their heart" (Acts 2:37). Once the conversion process begins, Paul tells us that God sends forth "the Spirit of his Son into your hearts" (Gal. 4:6). Does that mean if you do not feel of His Spirit in your heart that you aren't converted? The author believes it does.
Critics are mistaken if they think Latter-day Saints only put their trust in physical sensations in their chests. Perhaps we have focused too much on the earlier phrase of D & C 9:8 where the Lord tells Oliver Cowdery that his "bosom shall burn" within, and we sometimes miss the most important part of that sentence: "you shall feel that it is right."
We have been commanded to "trust in that Spirit which leadeth to do good--yea, to do justly, to walk humbly, to judge righteously; and this is my Spirit" (D & C 11:12). We know that the fruits of this same spirit are "love, joy, peace, longsuffering, gentleness, goodness, faith, meekness, temperance" (Gal. 5:22, 23). It is this Spirit with his many "fruits" of good character that we strive and pray for, not just a "burning in the bosom."
Nevertheless, the Bible teaches that feelings of the Spirit are often experienced as a burning in the bosom. Two disciples who were on the road to Emmaus were visited by the resurrected Lord. They didn't recognize him with their eyes, nor because of their knowledge of the scriptures. They recognized him when "their eyes were opened" and they recalled: "Did not our heart burn within us, while he talked with us by the way, and while he opened to us the scriptures?" (Luke 24:32)
Alma teaches us that to be born again is a spiritual process that affects the heart and begins as we receive Christ. He asked members of the Church, "Have ye experienced this mighty change in your hearts?" (Alma 5:14). True conversion is an experience of the heart--it can't come solely from reading the Bible, since the Bible as we know it only came into being in the 4th century AD. Many early Christians died in the Roman Coliseum. Why were they willing to die? Because of a conviction of the heart. For centuries after the Bible canon was formed, Christians still did not have access to it. Many were actually forbidden to read it.
Detractors who are sometimes "past feeling" poke fun at the spiritual feelings of one's heart. They have even likened it to indigestion from too much pizza. Perhaps some have become so numb to feelings of the Spirit that they do not know what it is like to be "pricked in their heart." Instead they mock those who attempt to describe a spiritual event with common words.