Assuming that God cannot or is not willing to reveal Himself to people. There are different religions - some are made by men acting in good faith (like neo-platonism or Indian philosophu or Confucionism), some are suspect like Scientology, others claim to come from revelation like Christinianity or Islam. Man-made does not mean to be false (people can speculate correctly) and Revelation can be false or true.
Only way to sort it out is to search, study, compare and test. Dismissive platitudes cannot substitute the genuine quest for the truth, their only purpose is to find excuse to live the animalistic life and to silence one's conscience.