There are many people I know that sin all year except in the month of Ramadan they become very religious and do everything right. But when Ramadan is over they return to sinning. The sinning they do is drink alcohol, zina (adultery), not pray much, partying...etc.
When I ask them why, they say that they can sin the whole year and when they do Ramadan right, Allah will erase their sins from previous year because of the good deeds they made in Ramadan. Is this true?