Here we find life gained and life lost. Both life gained and lost have to do with what we pursue and steadfastly desire in our walk on earth. It is no shock to us to learn that those who are steadfast in their desire and pursuit of righteousness are those who receive life. The word "steadfast" here means to set something up so that it will be firm and established. Here it refers to how someone views righteousness - and pursues it in their lives. Are you building a life whose foundation is laid in God's view of righteousness - or more simply put, in what God says is right? That is the life Christ referred to in Matthew 7 when He spoke about foundations. The one who hears the Word of God and heeds it - he is the man who has built his foundation on a rock. When the winds and storms of life come upon that man, as they surely will, his house will stand. That is why the steadfast in righteousness will attain to life.
The life lost is the one that is actively pursuing evil. Consider King Ahab in the Old Testament, along with his wicked wife, Jezebel. They pursued evil together. They were the poster couple of pursuing wickedness and sin. They excelled in it - and ran after it with an ever-growing lust for more. They worshipped false gods, stole, killed, and plotted their way to the top. When at the top they continued in their ways of evil - and heartily encouraged all of Israel to follow their foolish example. It is no wonder then that they both brought about their own death.
Ahab foolishly ignored the prophetic statements of Miciah, who warned him that God had allowed a deceiving spirit to move among Ahab's false prophets - so that he could be lured to his death in battle. Ahab's response was to imprison the prophet - and have him fed with barely enough bread and water to survive until he returned from battle. Miciah's fateful last words to him were, "If you return, the Lord has not spoken through me." In another desperate but foolish move, Ahab then disguised himself and did not wear his royal robes into battle. Thinking he had cheated death and God - he went into battle feeling safe. We read in Kings that a random archer shot an arrow into the air - and God guided that arrow so that it hit a joint in Ahab's armor. Badly wounded, he retreated to watch the battle from a distance until he died in his chariot.
Jezebel, having learned of a plot to destroy her family and their legacy in Israel, painted herself and called to her executioner from a tower. Thinking herself safe there - her executioner called for the men in the tower to throw her down. They did so and Jehu crushed her beneath his horses and chariot wheels. These two who pursued evil so passionately both brought about their own death because of their rebellion against God.
In Deuteronomy God reminded Israel that He put before them life and death. There was a choice for them. If they pursued evil and rebellion against God - they needed to know that their sin would find them out. They would be pursued by the very One against whom they rebelled. They would learn that He was not impotent as they thought. They would learn that the One they defied is God - and that He will prevail. They will also bring about their own death with the evil they think frees them from His authority. But life is also available to us. It is received by pursuing righteousness steadfastly. What is amazing to those who receive that righteousness is that to pursue it, one must pursue by faith. The just (righteous) man lives by faith. Their steadfastness is gained by rejecting their own works - and turning to God who Himself will declare them righteous as a gift. They will learn that the only way of being steadfastly righteous, is to steadfastly cling to God's gift of righteousness which comes only through His Son, Jesus Christ. That, dear ones, is the only way we can be steadfast in righteousness - and thereby know life.