Aren’t Some Unbelievers Sincerely Seeking Truth?

Questions about whether there are scriptural explanations for why people don’t think God exists other than that they’re “suppressing the truth in unrighteousness” and how to make the case for apologetics to a pastor who uses 1 Corinthians 2 to argue against it.

• Are there scriptural explanations for why some people don’t accept the existence of God other than that they’re “suppressing the truth in unrighteousness” or “fools saying in their hearts there is no God”? 
• How can we make a case for apologetics to a pastor who uses 1 Corinthians 2 to say it isn’t necessary and we should only be sharing the simple gospel?