It is not one's worship system that determines an eternal reward, but what is in that person's heart.
As to the question of the 400+ denominations who all claim Christ, most think that God will sort it all out in heaven. That said, most of those same folks refuse to set foot in a building not bearing the name of their denomination.
Some churches believe that all denominations except their own will be banished into hell. Among these are Jehovah’s Witnesses, Mormons, and Catholics, to name a few. Calvinists (which include several denominations) think they’re chosen by God to be saved, while the rest are likewise chosen to be condemned. My own church, the church of Christ, maintains that they are the One True Church, although the criteria used is legalistic and subjective.
Jesus said that many who thought they were Christians, and who were mightily engaged in Christian service, will find themselves rejected on Judgment Day. (Matt 7:21ff) In the context, the great qualifier of who gets into heaven will be, "whoever does the will of the Father." The Father’s will has very little to do with a church's worship model and much to do with a person's motives and love for their fellow human beings (Matt 25:31ff).
Thus, it isn’t what creed you hold to, what version of the bible you thump, or what name is painted on the church sign—it’s the one who does God’s will. The old verse, “not my will, but Your will be done,” is what will separate us at the Resurrection.
Jesus summed it up best: “Unless you humble yourself and become like a little child, you will not even see the kingdom of heaven.” (Matt 18:3) (Emphasis mine)
