In their book, "Growing Up Duggar," the Duggar parents, Jim Bob and Michelle, explain their reasoning behind this strict policy. They believe that premarital intimacy can lead to a number of problems, including temptation, regret, and a decreased ability to bond emotionally and spiritually with a spouse. They also believe that waiting until marriage to engage in intimate activities helps to protect the purity and sanctity of marriage.
The Duggars' views on premarital intimacy are consistent with the teachings of many conservative Christian denominations. These denominations believe that sex is a gift from God that should be reserved for marriage and that any sexual activity outside of marriage is a sin.
While some people may disagree with the Duggars' strict views on premarital intimacy, it is important to respect their beliefs. The Duggars are simply following what they believe to be the right thing to do according to their religious convictions.