Household Salvation and Infants
"...that he may know to refuse the evil, and choose the good...For before the child shall know to refuse the evil" (Is. 7.15,16).
Eternal life is based on the individual, but salvation is based on the household. For the Scriptural proof see Infants who Die and Watchman Nee’s book, Good Confession, pp. 97-114. What this means, I believe, is that the position of overcoming in Christ starts with the household, where a believer in the household affecting the rest of the members of the family household giving opportunity for salvation individually.
A different rule applies to infants who die. After David's son died when he was only seven days old (2 Sam 12:18), David said: "I will go to him." (2 Sam 12:23) He believed that this child who had died, was saved. We may also believe that our infants who have died are saved, because God has made specific promises to those who believe in Him. (Acts 16:31) - Dr. Marais.
Isa 7:14 Therefore the Lord himself will give you a sign: behold, a virgin shall conceive, and bear a son, and shall call his name Immanuel.
Isa 7:15 Butter and honey shall he eat, when he knoweth to refuse the evil, and choose the good.
Isa 7:16 For before the child shall know to refuse the evil, and choose the good, the land whose two kings thou abhorrest shall be forsaken (northern Israel which is Lebanon and southern Syria today, and Aram, i.e. around Damascus of Syria today).
This is a double fulfillment of Isaiah's son of a virgin, possibly another wife. This will be true for all children, not just Jesus Christ, eventually one day, recognizing these evil regions, inhabitants therein. God promises to preserve a remnant of the 12 tribes of all of Israel in the days of Solomon since Rev. 7.1-8 becomes that remnant that will return. At a very young age, we begin to have free-choice.
A child may be saved in my household because I am saved, but I do not think children are saved before the time of the age of accountability always since God's foreknowledge can know if that soul would have come to Christ, and that may be why God let them go, allowing departure from the flesh to happen, since it was going to happen anyway in certain cases. What is the age of accountability? It approximates 8 years for most children IF each day represents a year,
Gen 17:12 And he that is eight days old shall be circumcised among you, every man child in your generations, he that is born in the house, or bought with money of any stranger, which [is] not of thy seed.
In order for an infant who is saved to occupy the new city as a pillar, that child will need to mature and "spiritually" age in "outer darkness". The same holds true for an elder in which age has no meaning for transubstantiation of the resurrected.
And Paul's words indicate salvation before the age of accountability when before he was without the law: "For I was alive without the law once: but when the commandment came, sin revived, and I died" (Rom. 7.9).