1 Pet 3:18
18 For Christ died for sins once for all, the righteous for the unrighteous, to bring you to God. He was put to death in the body but made alive by the Spirit,
(NIV)
Eph 2:8-9
8 For it is by grace you have been saved, through faith-- and this not from yourselves, it is the gift of God--
9 not by works, so that no one can boast.
(NIV)
Heb 12:5-8
5 And you have forgotten that word of encouragement that addresses you as sons: "My son, do not make light of the Lord's discipline, and do not lose heart when he rebukes you,
6 because the Lord disciplines those he loves, and he punishes everyone he accepts as a son."
7 Endure hardship as discipline; God is treating you as sons. For what son is not disciplined by his father?
8 If you are not disciplined (and everyone undergoes discipline), then you are illegitimate children and not true sons.
(NIV)
Why should Christians bother to be pure? True, we won't lose our salvation (Romans 6:23 with Romans 11:29 and John 10:28-29). But we should bother because God is pure and He asks the same of us. If that isn't enough reason for some, another reason is that His loving discipline can get as rough as it takes to get us back on the track.
And that can be pretty rough:
2 Sam 12:7-13 Then Nathan said to David, ".... This is what the LORD, the God of Israel, says: 'I anointed you king over Israel, and I delivered you from the hand of Saul.
8 I gave your master's house to you, and your master's wives into your arms. I gave you the house of Israel and Judah. And if all this had been too little, I would have given you even more.
9 Why did you despise the word of the LORD by doing what is evil in his eyes? You struck down Uriah the Hittite with the sword and took his wife to be your own. You killed him with the sword of the Ammonites.
10 Now, therefore, the sword will never depart from your house, because you despised me and took the wife of Uriah the Hittite to be your own.'
11 "This is what the LORD says: 'Out of your own household I am going to bring calamity upon you. Before your very eyes I will take your wives and give them to one who is close to you, and he will lie with your wives in broad daylight.
12 You did it in secret, but I will do this thing in broad daylight before all Israel.'"
13 Then David said to Nathan, "I have sinned against the LORD." Nathan replied, "The LORD has taken away your sin. You are not going to die...."
Aloha in Jesus