Unfortunately, this statement by Jesus has been used by some to prove that Christians are obligated to do certain things in order to be saved - that our salvation is somehow dependent on the things that we do (or fail to do). For them, this verse of Scripture demonstrates that salvation is not simply a matter of accepting and believing in what Christ has done for us - it is absolute proof that we have a part or role to play in our own salvation! They also see this passage as absolute proof that salvation is something that can be lost or withdrawn. What about all of that? Does this statement by Christ somehow modify, overturn, or contradict other seemingly clear Biblical statements about salvation through Jesus Christ?
According to the Gospel of John, Jesus said: "For this is how God loved the world: He gave his one and only Son, so that everyone who believes in him will not perish but have eternal life. God sent his Son into the world not to judge the world, but to save the world through him." (3:16-17) This clear statement by Christ underscores one of the foundational teachings of the Christian Church - that salvation is through Jesus Christ, and that anyone who would receive this gift must believe that Christ is his/her Savior. And, as one would expect of a teaching so fundamental to the religion, it is supported by many other passages of the Bible. The same gospel account also informs us that Christ once said that HE was the ONLY way to God the Father. (John 14:6) In the Gospel of Luke, we are told that Jesus said that he came to this earth "to seek and save those who are lost." (Luke 19:10)
It is also clear that Christ's apostles taught the same thing about salvation. We read in Paul's epistle to the saints at Ephesus that "God saved you by his grace when you believed. And you can’t take credit for this; it is a gift from God. Salvation is not a reward for the good things we have done, so none of us can boast about it." (Ephesians 2:8-9) Paul told the Christians at Rome that his message about faith was "If you openly declare that Jesus is Lord and believe in your heart that God raised him from the dead, you will be saved. For it is by believing in your heart that you are made right with God, and it is by openly declaring your faith that you are saved." (Romans 10:9-10) Likewise, in the same letter, he wrote that "For the wages of sin is death, but the free gift of God is eternal life through Christ Jesus our Lord." (Romans 6:23) Paul wrote to Titus that "When God our Savior revealed his kindness and love, he saved us, not because of the righteous things we had done, but because of his mercy. He washed away our sins, giving us a new birth and new life through the Holy Spirit. He generously poured out the Spirit upon us through Jesus Christ our Savior. Because of his grace he made us right in his sight and gave us confidence that we will inherit eternal life." (Titus 3:4-7) In the book of Acts, we are told that Peter preached that "Jesus is the one referred to in the Scriptures, where it says, 'The stone that you builders rejected has now become the cornerstone.’ There is salvation in no one else! God has given no other name under heaven by which we must be saved." (Acts 4:11-12)
So, in the light of all of these clear passages about salvation through Jesus Christ, how can Christ's statement about enduring to the end be interpreted to mean that Christians have a role to play in their own salvation? The short answer is: IT CAN'T! Salvation is either a free gift that we receive because of what Christ did for us, or it isn't! Now, it is clear that humans are required to repent of their sins when they accept Christ's sacrifice for their sins (Acts 2:38), and that our acceptance/belief in the efficacy of Christ's sacrifice will result in us walking in newness of life and exhibiting the fruits of God's Holy Spirit (Ephesians 4:24 and Galatians 5:22-25). Even so, it is not the doing of those things that earns us salvation (For no one can ever be made right with God by doing what the law commands - Romans 3:20) - rather, the doing of those things is a clear indication that we have accepted salvation through Jesus Christ! Conversely, anyone who continues to live a life of habitual sin clearly hasn't accepted Christ as his/her Savior!
What was Christ talking about when he made that statement about enduring to the end? His disciples had just asked him about the destruction of the temple and the circumstances surrounding his return to this earth and the end of the age. (Matthew 24:3) Hence, his remark about enduring to the end must be interpreted within the context of his answers to those questions! In other words, Christ remarks here refer specifically to the events which his disciples had asked him about - not necessarily about salvation in the broader spiritual sense! Moreover, even if we ignore the context and insist that Christ is talking about salvation generally, we cannot escape the fact that the original Greek word translated into English as "endure" is better described as maintaining something (see Strong's Concordance) - that is faith in Christ as our Savior! In other words, the person must continue to believe that they have received salvation through Jesus Christ! Paul told Timothy that he had maintained his faith and finished his race (II Timothy 4:7). In other words, he had endured to the end of his life. Hence, we see that Jesus was speaking about maintaining faith in him, NOT about continuing to be obedient to a list of dos and don'ts or about holding on to a package of doctrinal beliefs!
In conclusion, it is clear that Scripture teaches that Christians must believe in the efficacy of Christ's sacrifice for the remission of their sins and the accomplishment of their salvation. In other words, their salvation is NOT dependent on them or ANYTHING that they do or don't do! The people of Christ's day wondered what good works that they could do to gain God's favor, and he told them: "This is the only work God wants from you: Believe in the one he has sent." (John 6:29) As for our receipt of that salvation, we have already received that guarantee through the Holy Spirit. (Ephesians 1:13-14) The author of the epistle to the Hebrews wrote: "For you have need of endurance, so that after you have done the will of God, you may receive the promise: 'For yet a little while, And He who is coming will come and will not tarry. Now the just shall live by faith; But if anyone draws back, My soul has no pleasure in him.' But we are not of those who draw back to perdition, but of those who believe to the saving of the soul." (Hebrews 10:36-39) Who has done the will of God? THE ONE WHO BELIEVES (and maintains that belief until he/she draws their last breath)!