JOEL - The short answer to your question is, yes and no. Now here comes the long answer.
According to the LDS religion, a person must learn, accept, and live the Gospel of Jesus Christ as taught in the LDS Church, in order to enter into the Celestial Kingdom. A belief in any other religion or no religion will send them to one of the lower kingdoms of heaven. However, anyone, no matter what religion they do or do not belong to, will have the opportunity to hear and accept the true Gospel of Jesus Christ in the Spirit World(Spirit Prison) after they die, if they did not have the opportunity to find out about it in this life. After they do hear and accept it in the Spirit World they will have the opprotunity to enter into the Celestial Kingdom after the final judgment; provided that someone has performed the necessary saving ordinances in an LDS temple for them here on earth. If someone was given adequate opportunity to hear and accept the Gospel while here on earth, but did not accept it, they probably would not accept it in the Spirit World either and would therefore not be able to go to the Celestial kingdom.