The "natural walk" of those who are in the Spirit is spiritual. When a believer has had his eyes also opened to the fact that he has died and is free from the law and therefore married to the Lord Jesus, he must believe by faith that God has put the law of the spirit of life in Christ within him, to operate the victory of God within him against the law of sin and death.
You have been saved with a great salvation. While you were yet a sinner, rebellious and hostile to God, He, out of mercy, chose you unto salvation. He says, "You did not choose me but I chose you" (John 15:16). He chose you not because of any special merit, but because of His love for you. From the beginning He saved you by grace and not by merit.
It is God's will that all who have been made into new creatures through union with the Lord Jesus in His death, resurrection and exaltation should know for certain that they have eternal life and, therefore, will never perish. This assurance that they have permanently passed from death unto life in Christ, that the Lord will surely keep them to the end, that because they are in Christ they will be in heaven, is the right of the true believer, and he ought to enter into his full inheritance.