What happened in that case?
King David was not saved while he committed his sins of adultery and murder.
#1.
Numbers 35:16-18 says it only takes on act of murder to be a murderer; And
Leviticus 20:10 says it only takes on act of adultery to be an adulterer.
#2. Jesus Himself regarded just looking at woman once as an act of adultery (
Matthew 5:28).
#3. John says, "No murderer has eternal life abiding in them." (
1 John 3:15).
#4.
Proverbs 6:32 says "Whosoever commits adultery with a woman lacks understanding: he that does it destroys his own soul."
#5. Jesus Himself says that just looking at a woman in lust (Which is adultery) is potential for a person to be cast bodily in hell fire (See
Matthew 5:28-30).
#6. David needed to confess of his sin in order to be forgiven (See
Psalms 51).
#7.
1 John 1:9 says if we confess our sins he is faithful and just to forgive us our sins and to cleanse us from all unrighteousness. 1 John 1:7 tells us to walk in the light as a part of the blood of Jesus to cleanse us of all sin. This lines up with Proverbs 28:13 that says he that confesses and forsakes sin shall have mercy.
#8.
Revelation 21:8 says, "But the fearful, and unbelieving, and the abominable, and murderers, and whoremongers, and sorcerers, and idolaters, and all liars, shall have their part in the lake which burns with fire and brimstone: which is the second death." Murderers and whoremongers will be cast into the lake of fire. All liars will be cast into the lake of fire. ALL liars, and not just some. NO murderer has eternal life abiding in them (
1 John 3:15).