Suppressing the conscience or deliberately violating it is deadly to our spiritual well-being. To disobey the conscience is itself a sin (Romans 14:14, 23; James 4:17), even if the conscience is ignorant or is misinformed. And to suppress the conscience is tantamount to searing it with a hot iron (1 Timothy 4:2), leaving it insensitive and thereby dangerously removing a vital defense against temptation (1 Corinthians 8:10).
John MacArthur