And this gospel of the kingdom will be preached throughout the whole world, as a testimony to all nations; and then the end will come.
Everyone would have heard the word of YHWH by the time of what is predicted in Revelation. Yehshua was sent to this earth to save those who are not His followers. But, to recieve His salvation, you have to accept it. If you do not, you shall be held accountable for your sins. It's kind of like overdrafting you're bank account, and they offer to fix it and pay the debts for free. They ask you if you would like them to, and you can either say yes or no. You still have to make the choice.
P.S. If you actually read the Bible, the ideas never contradict themselves.