Almsgiving Will Not Atone for Sin Unless the Life Be Changed
We must beware, however, lest any one should suppose that gross sins, such as are committed by those who shall not inherit the kingdom of God, may be daily perpetrated, and daily atoned for by almsgiving. The life must be changed for the better; and almsgiving must be used to propitiate God for past sins, not to purchase impunity for the commission of such sins in the future. For He has given no man license to sin, although in His mercy He may blot out sins that are already committed, if we do not neglect to make proper satisfaction.
Source: The Enchiridion (New Advent)