Only God knows who truly becomes saved and who doesn't.  That's because he can see into our hearts and others can't.  He knows if we were sincere when we told Him we accept Jesus as our Savior and want to have a new life in Him.  Some people act like they are truly saved, and some people don't.  But we cannot really know for sure.

 

Follow-up is a very important thing for the newly saved.  But even follow-up cannot insure a persons salvation was real.  If they weren't totally sincere in their heart when asking God for salvation, no amount of follow-up is going to make a bit of difference.  It might encourage them to "play the role" a bit longer, but without the Holy Spirit taking up residence within them, they will quickly stop the role playing and continue to live the life of an unrepentant sinner.

 

I believe that when a person becomes truly saved, God already has plans on how to get the newly planted seed of the new nature watered and fertilized.  It could be through follow-up after the hand was raised and the altar call by the particular church the person was saved at, or it could be by any number of ways that God sees fit to bring about.

 

Just as we can't know for sure if a person was sincere when asking for salvation, we also can't force them to "stay saved" through follow-up.  If they aren't sincere, they aren't saved.  Follow-up assumes they are truly saved, and it will either help them progress in their new life, or it will bring about feelings of guilt for being a faker, and cause them to eventually abandon their pretense.

 

Diane, In your sister-in-law's case, she surely knew why she asked God for salvation, even if she wasn't sincere.  And follow-up by her family and friends would have either turned her off completely, or it would have encouraged her to become sincere and become truly saved.