Question
The phrase 'knock on wood' has become common to ward off the evil eye. Are we resembling Christians when we say this phrase? For them, it means knocking on the cross. Is there a sin in using it?
Answer
I say, and with God's success: If the phrase is specific to them and symbolizes a belief they hold, and thus has become closer to a slogan unique to them, then it is not permissible to use it; otherwise, it is permissible. And God knows best.