If all the problems of religion as pertaining to life, worship, and salvation were reduced to just one, it would be, a rejection of the truth. I believe it's fair to say the vast majority don't believe in absolute truth with regards to religion. This is especially true in our society. For most will only accept "parts" of the Bible which are believed to be contributive to their own beliefs, feelings, traditions, and opinions.
Our generation has come to accept truth as being subjective, and even the need for it as pertaining to salvation, as unimportant. The practice of most is to fill their heads with good hopes and promises, all of which have originated in their own minds, and in the next life God will honor these. This ignorance stems from a rejection of having to study the Bible and submit to all of it as "the" means of getting to heaven (Acts 20:27). Furthermore, it is safe to say that most haven't even heard of a "2 Thessalonians", nor its chapter 2, verse 10, which reads, "And with all deceivableness of unrighteousness in them that perish; because they receive not the love of the truth, that they might be saved."
Our generation will one day stand doomed in Judgment for we have the truth readily available and yet most people don't want it (Hosea 4:6). As in the times of Amos, Jeremiah, and Isaiah so it is with us, the "famine" of hearing the truth is upon us (Amos 8:11, Jer. 5:30-31; Isaiah 30:10).
Yet, no matter how bleak it seems, there are souls to save! Our mission is to seek, find, and "bring out the Lots" so they may be saved (Gen. 19). Remember, there weren't 10 righteous souls in Sodom and Gomorrah (Gen. 18:23-32). Only Noah's family, 8 souls, received the truth in his lifetime (Gen. 6-9). God measures us by our efforts to proclaim the truth, not by the response.