For the most part, because people are lazy. That's why you'll hear "I just have to accept the Lord, Jesus into my heart and that's all I need". Garbage like that, which they delude themselves into thinking is true, is simply their excuse for not doing what they need to be doing. You may also hear of their claims that they preach through their various car washes, bake sales, and etc...etc...they put on several times a year. It's more garbage. If anyone is claiming to be a Christian, then they MUST follow all of Jesus' commands for his Christian disciples, including that of preaching the good news of the kingdom from door-to-door and from town-to-town, wherever people are. \n\nIt's not simply a command that Jesus laid upon his followers, it's a Christian obligation to go out and preach about God's kingdom to other people.\n\nJehovah's Witnesses VOLUNTEER their time and effort to do just this very work, and as their annual reports show, their active 6.5 million members are putting in over 1 billion hours EACH YEAR to help others come to know the truth.