​Most Christians find comfort in the no-strings- attached  “whoever” in the unadulterated Gospel Message, encapsulated in John 3: 16, and the assurance of salvation (1) that the criminal on the cross on the side of our Lord received (2).
The criminal on the cross was as much saved as anyone else, including those were born-again early in life.  His post salvation spiritual life was only going to involve a few hours, with very little opportunity to bring any further glory to God.   
Yet, the recording of his brief conversation with the  Lord has brought the same assurance to others who were to be saved in death-bed scenarios throughout the course of the upcoming Church Age.
But for most of us, God has a plan that involves a lot of objectives for us to accomplish before our appointed time of departure arrives. God desires that we move forward in the post salvation spiritual life of discipleship.  
Biblical discipleship is not for the purpose of retaining salvation that cannot be lost (3).  It is for the purpose of bringing maximum glory to God by being conformed to the likeness (in thinking, speech, and behavior) of our Lord and Savior, Jesus Christ (4).
Just as Satan has a plan to deceive Fallen Man regarding what is required to be saved, he has a plan to deceive born-again believers as to what  post (after) salvation discipleship is really all about, as well. 
Scripture concedes that Satan has done well in this area of spiritual combat, referring to him as being the “god” of this world in 2Cor. 4: 4, and the one who “deceives the whole world”  in Rev. 12: 9.
Satan has done, and is doing so, by promoting false Gospel Messages as the means to receive eternal life and to secure residency in Heaven. Satan promotes good human deeds and behavior as the means to “earn” Heavenly reward. He does so mainly through people he has deceived that unwittingly become the blind leading the blind down the wrong road.
Good deeds and behavior are characteristics of a Christian’s life here on Earth, but they are NOT what saved him or her.
Participation in the activities required by these false Gospels, the production of human good deeds, and living by standards of generally-accepted moral behavior, appeal to the arrogance in the FALLEN Man, as they appear to provide fallen Man with the means to save himself, and the means to earn Heavenly reward.
The truth is, an unbeliever can do all of the above, but will never-the-less find himself being tossed into what the Bible calls the lake of fire when the Rev. 20: 13-15 event take place.
Salvation is eternally-secured as a result of making a one-time decision to believe, when he or she is presented with the unadulterated Gospel Message.  
Post (after) salvation discipleship, that being the study and application of the Word of God, is initially for the individual believer’s edification, with the long-term objective of ongoing participation in the Great Commission (5).
The devil’s deceptive traps are always baited with a degree of truth. 
It IS true, for example, that we were all born “that way,” having come into this world with a sin nature that is bent towards sin, and that is inherently hostile towards God and the things of God. 
But it is a lie that says there is nothing that can or must (6) be done about it! 
This fallen nature manifests itself in differently in each individual or groups of individuals, but the end result of ANY sin (7) is one form of death or another (8).
What form of sin that can be a great temptation and desire for oneself will be of no interest to someone else.  What form of sin that can be a great temptation and desire for someone else, is of no interest to us.
There are, for example, some liars that would not steal, and some  thieves that would not lie. But as James 2:10 makes clear, this doesn’t matter, as the breaking of any ONE of God’s laws, puts ALL of us in the same stinking, sinking, boat of sinners.
End of Part Two
(1) Rom. 8: 1 (2) Luke 23: 43 (3) Rom. 8: 1 (4) Rom. 8: 29 (5) Matt. 28: 19, 20 (6) John 3: 7  (7) James 2: 10 (8) Rom. 6: 23