
and

on the not fighting.
Saving faith is a gift from The Holy Ghost, which can be accepted or refused (free will), otherwise it would be irresistible grace, as in Calvinism.
Once saved, always saved (OSAS). As I understand OSAS, once a person is saved through saving faith (NO WORKS) (faith alone in Christ alone, in accordance with Scripture alone, by the grace of God alone, to the glory of God alone), God will not let the person go, that the person is still saved, no matter what. Otherwise Salvation would be faith plus works. This is what virtually everyone on the board believes.
Sin after Salvation. People still have free will, and still have a sin nature, so we still sin. We try not to sin because of the Holy Ghost working inside us, but we still have free will.
When I was a little girl, my Maternal Grandmother used to ask me, "Wouldn't it be terrible if Jesus came back right now and found [whatever my latest transgression(s) was/were]?"

This is what I needed at the time, along with getting scared about Hell with a very graphic description of the place and what happens after death to non-believers and contrasting with believers. Now that I know more, I know Jesus already knew what I was doing, had done, and would do, even before I did it
If someone is sinning, then the process in Matthew 18 (Church discipline), which starts with one person going to the sinner privately, etc. When the sinner is a child, it's a very easy situation because the Parent(s) deal with it both as a fellow Christian and as the Earthly authority, as appointed by God. It may or may not be quite as simple when it is the wife, depending on whom she has offended.
*Some Christians, like the Lutherans, believe that free will also allows a person to knowingly and deliberately renounce his or her faith (give the gift of Salvation back) and become unsaved because otherwise no true free will and it would be a form of irresistible grace, as in Calvinism. This renouncing of faith does not include under duress like torture, does not include losing it by sinning, and does not include having God, the devil, or any person take it away involuntarily. The person can also later choose to re-accept the gift of saving faith. Those, who believe OSAS, say that a person, who deliberately renounces faith (other than under duress, like torture) wasn't saved in the first place.
**Some Christians believe that once saved, a Christian doesn't ever sin again. I have no explanation for this.
15 Moreover if thy brother shall trespass against thee, go and tell him his fault between thee and him alone: if he shall hear thee, thou hast gained thy brother.
16 But if he will not hear thee, then take with thee one or two more, that in the mouth of two or three witnesses every word may be established.
17 And if he shall neglect to hear them, tell it unto the church: but if he neglect to hear the church, let him be unto thee as an heathen man and a publican.
Matthew 18:15-17, KJV
Train up a child in the way he should go:
and when he is old, he will not depart from it.
Proverbs 22:6, KJV
1 Children, obey your parents in the Lord: for this is right.
2 Honour thy father and mother; which is the first commandment with promise;
3 That it may be well with thee, and thou mayest live long on the earth.
4 And, ye fathers, provoke not your children to wrath: but bring them up in the nurture and admonition of the Lord.
Ephesians 6:1-4, KJV
19 Speaking to yourselves in psalms and hymns and spiritual songs, singing and making melody in your heart to the Lord;
20 Giving thanks always for all things unto God and the Father in the name of our Lord Jesus Christ;
21 Submitting yourselves one to another in the fear of God.
22 Wives, submit yourselves unto your own husbands, as unto the Lord.
23 For the husband is the head of the wife, even as Christ is the head of the church: and he is the saviour of the body.
24 Therefore as the church is subject unto Christ, so let the wives be to their own husbands in every thing.
25 Husbands, love your wives, even as Christ also loved the church, and gave himself for it;
26 That he might sanctify and cleanse it with the washing of water by the word,
27 That he might present it to himself a glorious church, not having spot, or wrinkle, or any such thing; but that it should be holy and without blemish.
28 So ought men to love their wives as their own bodies. He that loveth his wife loveth himself.
29 For no man ever yet hated his own flesh; but nourisheth and cherisheth it, even as the Lord the church:
30 For we are members of his body, of his flesh, and of his bones.
31 For this cause shall a man leave his father and mother, and shall be joined unto his wife, and they two shall be one flesh.
32 This is a great mystery: but I speak concerning Christ and the church.
33 Nevertheless let every one of you in particular so love his wife even as himself; and the wife see that she reverence her husband.
Ephesians 5:19-33, KJV