1 Corinthians 8:2

If any man thinketh that he knoweth anything, he knoweth not yet as he ought to know;

'thinketh' -'supposes' (NASV) 'Its good to know, but then there is an attitude toward your knowing. There is. healthy and an unhealthy way of thinking that you know.' (McGuiggan p. 123)

'knoweth' -lit., 'has come to know' (Vincent p. 226) 'The perfect tense..implies that they consider themselves to have arrived as far as knowledge is concerned..the one who thinks he is "in the know"..' (Fee p. 367)

Note:

Paul isn't saying that we can't know or know anything for sure, or even that we can't know any biblical subject with absolute certainty (1 Corinthians 8:4-6; Ephesians 4:4; Ephesians 5:5 'For this you know with certainty..'). Rather, he is talking about. knowledge that lacks love,. knowledge is this nothing more than arrogance.

'He who thinks that "knowing" ends with gaining the correct view and doesn't understand that knowing is. means to an end (i.e. serving God and the ignorant), he doesn't know as he ought.."It is not what to know, but how to know, which includes all real knowledge."' (McGuiggan pp. 123-124)

'as he ought to know' -'he has not yet reached that knowledge which he ought to have reached.' (TCNT) 'He hasn't learned that gaining knowledge isn't the purpose of life; it's one of the elements essential to living life for God and people.' (McGuiggan p. 124)