All scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness:
2Timothy 3:16
There is nothing more important to the Christian faith than the Bible itself. Everything a Christian believes the origin of sin, the virgin birth, the substitutionary death, the bodily resurrection of Jesus--everything we believe--we believe it because we read it in the Bible. So, if we have no confidence in our Bible, we can have no confidence in our faith. It is of great importance then, that we are able to answer the question, "What makes you think the King James translation is the inspired, preserved translation for English speaking people?"
Perhaps you get your answer from your knowledge of the Greek and Hebrew that allows you to point out all the difficulties in the various texts. Maybe your answer comes from a thorough knowledge of history that allows you to site the major influences of the translators who worked on various translations. Personally, I need a simpler answer.
My answer lies in the fact that the King James Bible uses manuscripts that date back to Bible times, while modern translations all rely heavily on manuscripts that were found in the 1800s. That means that for hundreds of years, the manuscripts used in contemporary translations were either lost to or rejected by the church while the manuscripts that were used in the King James Bible have a continuous history of usage by the church. To that fact, I ask two questions.
1. If I cannot trust the manuscripts that God has preserved and used for over 2,000 years, the manuscripts that He used to evangelize the world, found America, and ignite the modern mission's movement, why would I trust manuscripts that were lost or rejected by the church for 1500 years?
2. If I can trust the manuscripts God preserved to produce the King James Bible, why do I need anything else?