The ruling of that is that the statement 'Ramadan kareem' is not correct. Rather it should be said 'Ramadan Mubarak', or whatever is similar to it, because it is not Ramadan itself that gives so that it can be kareem (generous), in fact it is Allah who placed the grace in it, and made it a special month, and a time to perform one of the pillars of Islam.
It is as if the one saying this thinks that the sacredness of the time allows him to commit transgressions. This is turning around what the people of knowledge have said that bad deeds are greater at special times and places, the opposite of what the one saying this imagines. They say that it is obligatory to fear Allah - the honourable and majestic - at all times, and in all places, especially in special times and special places.
Allah - the honourable and majestic - says,
O you who believe! Observing As-Saum (the fasting) is prescribed for you as it was prescribed for those before you, that you may become Al-Muttaqun (the pious - see V.2:2). [2:183]
Allah shows that the wisdom of fasting is taqwa (piety) of Allah - the honourable and majestic - by fulfilling His commandments and avoiding His prohibitions. It has been ascertained from the Prophet (pbuh) that he said, "Whosoever does not leave speaking falsehood, or acting with it or ignorance, then Allah has no need that he leaves his food and drink." Fasting is cultivation of the self, guarding it from the prohibitions of Allah, and not as this ignoramus says that due to the sacredness and blessing of this month it allows commiting transgressions.
From a collection of the Shaykh Ibn al-'Uthaymeen's fatwas, As`ilah wa ajwibah 'an alfaaz wa mafaaheem fee meezaan al-sharee'ah ("Questions and Answers on Expressions and Concepts in the Scale of the Shariah") printed by Maktab al-Da'wah of Britain