Here's an ironic thought
I think the idea of "strong" Christian as opposed to "weak" Christian comes from Paul's comments in Romans about the weaker brother???? No???
If that is so then it might help to understand that the idea behind the "weaker" brother is "sick in the soul" meaning that something makes them feel sick in their soul. This is the expression of how they feel when they believe something to be sin. So Paul speaks of one brother who can eat meat sacrificed to idols because they know the idols are nothing and another brother who, when confronted with the idea of eating meat sacrificed to idols, feels sick in their soul.
Which means it is technically the people who identify everything as being sin and fear what will happen if their children are allowed to engage in normal age expected behavior who are the "weaker" brother--they are the ones who feel sick in their soul when these childish behaviors occur. SO the more rules and regulations by which one lives, the "weaker" a believer they are according to Paul