Many interpret the Bible to say that one must confess Jesus is the Christ to qualify for salvation. The Bible also states that at some future date "all knees shall bow and all tongues shall confess that Jesus is the Christ." Does this mean that everyone despite our comportment in this life will be saved and go to heaven. Well, yes and no. This issue comes down to our understanding of salvation and heaven.
Paul discussed the redemption of the the body at the time of the resurrection by describing differing states of quickening, "there are bodies Celestial... Terestrial... and Telestial." These states are likened unto the differing glories of the sun, moon and stars in magnitude respectively. So, according to Paul all men will be resurrected, saved from hell, and redeemed to some level of glory by the grace of God. But, only those who are raised to Celestial glory not only receive salvation from hell but also exaltation.
What is the Mormon concept of heaven, salvation, and exaltation? Mormons believe that one who qualifies for the highest degree of Celestial glory will, together with their spouse to whom they have been married for time and eternity, live with God the Father and His Son Jesus Christ. They will receive perfect glorified bodies, will be able to progress in intelligence, power, and have eternal increase until they have become like God. They will have Eternal families and enjoy the same sociality enjoyed in this life. Some consider this concept of heaven and salvation as heresy, sacrilege, and blasphemy.
I desire an eternal family and eternal progression in the next life and these are things that other faiths have no concept of. Mormon missionaries are not telling people that they are going to hell if they don't become Mormons but that there is more to the next life than just heaven and hell. Ask yourself. What does you’re religion teach about the what heaven in like? What have you always felt it will be like? Do you want to just be saved from hell, or do you want an Eternal family and Eternal progression?