I will have to disagree with llovlygirl's view that it is up to us to retain our salvation because we may lose it. First of all we read in John 16 that Jesus has sent the Holy Spirit to convict of sin and to guide us into all truth. It is true that we will never be perfect until the day of transformation. However we are in a state of continual sanctification (the social change described earlier) We are to continue to grow to be more Christ like. The letter spoken of in Rev 2 to the Ephesians speaks not about the loss of salvation for the believer. For the church it speaks of its witness it has to its area. For the believer this means that God will remove His blessing upon your life and you will be an ineffectual Christian. Romans 8 clearly states that a believer's destiny is for sure all the way to glorification. while debate continues on the predestination meaning, one thing is sure about this. Whether free will or preordained, the true believer is already a citizen of heaven.
When we are saved, we are justified. This means that at the moment of our conversion, we recieve the standing of righteousness before God. Jesus died for all our sins past, present, and future. After our conversion, we recieve the gift of the Holy Spirit who guides us in our Christian walk. The closer the fellowship we maintain with God, the more we will feel the urgiing of the Spirit. Though we never will achieve the perfection of Christ, we must continue to press toward that goal. When Christ comes back to recieve His Church, we will be transformed and we will be given uncorruptible bodies that are set apart from the ravages and the nature of sin forever. If you have made Christ the Lord of your life, you are His forever. (John 10:27-30)