The focus seems to be discerning between the mature in the faith and those who are not yet grown beyond milk. The ones on milk cannot accept the weightier matters of wisdom. They need to strengthen their foundation. For some that may happen quickly, but I think in general it happens over time as we are tested by the trials and tribulations of life. Maturity in life matters may actually help, as a broader perspective is brought into play. People with more life experience should know themselves better, perhaps have better insight into at least their powerlessness and need for faith in Christ to accomplish what He has promised, for it is Him working through us.
1¶And I, brethren, could not speak unto you as unto spiritual, but as unto carnal, even as unto babes in Christ.
2I have fed you with milk, and not with meat: for hitherto ye were not able to bear it, neither yet now are ye able.
' Cannot speak ' CANNOT !
neither yet now are ye able.
NOT ABLE !
The same as the Natural man.
Thats why i believe the ' Natural ' man is a carnal believer. It means the same thing .