What is the difference between criticism and condemnation? And am I, by virtue of my job as a critic, committing a sin by criticising?
The basic difference between criticism and condemnation is that criticism is objective, whereas condemnation is something directed towards more personal aspects.
Healthy criticism is a form of analysis, and a process of careful evaluation which highlights good as well as bad points, and gives the subject its full dues, making excuses for any weaknesses if there is scope to do so.
Condemnation which only mentions the bad points, however, is a kind of attack, and anyone doing this is not being just.
Likewise there are various types, and various degrees of criticism, such as calm, serious criticism which has a rational style, and there is biting, spiteful criticism and wounding criticism. Each critic has a different style, and differs in choosing which words he uses. Look and see which kind you are!
Be objective and fair, and do not be harsh in your criticism.
If your official job happens to be that of a critic, then there is nothing wrong in that, sometimes a writer criticises a book and his criticism is all praise for that book, if it deserves it.
Criticism also requires study and knowledge, and has its own principles, and not everyone can ascend to, the rank of a true critic, or can claim this quality for himself.
Readers benefit from the criticism of the scholarly and fair minded critic, and so does the person whom he criticises, and the critic then is contributing to the advancement of literature and scholarship.