it comes from this:
For the unbelieving husband has been sanctified through his wife, and the unbelieving wife has been sanctified through her believing husband. Otherwise your children would be unclean, but as it is, they are holy.
(1 Corinthians 7:14)
what do you think this means?
Not what you think it means.
The Bible tells us we should not be unequally yoked with unbelievers.
14.Do not be unequally yoked with unbelievers. For what partnership has righteousness with lawlessness? Or what fellowship has light with darkness? The Book of 2nd Corinthians chapter 6
In that passage of 1 Corinthians 7. what is being said is, if one spouse is a believer and there are children in the household, the relationship is made legitimate, sanctified, because one unbeliever is yoked with one partner who has faith . And this in turn makes the children sanctified of that union, legitimate, rather than as illegitimate children.
The preponderating factor there is that the believing spouses faith insures a legitimate marriage.
Psalms 127:3 - Lo, children [are] an heritage of the LORD: [and] the fruit of the womb [is his] reward.
1 Corinthians 7:12-16 12To
the rest I
say this (I, not the LORD): If any brother has a wife who is not a believer and she is willing to live with him, he must not divorce her. 13And if a woman has a husband who is not a believer and he is willing to live with her, she must not divorce him. 14For the unbelieving husband has been sanctified through his wife, and the unbelieving wife has been sanctified through her believing husband.
Otherwise your children would be unclean, but as it is, they are holy. 15But if the
unbeliever leaves, let it be so. The brother or the sister is not bound in such circumstances; God has called us to live in peace. 16How do you know, wife, whether you will save your husband? Or, how do you know, husband, whether you will save your wife?
It should be noted that Jesus did not teach that Salvation comes by proximity to a believer.
If that were true, any person who is curious and enters into a church on Sunday is automatically saved due to crossing that threshold and being among Christians.