Alignment is one of the primary concerns of mid-to-high-level players. Align can be anywhere from -1000 (Satanic) to +1000 (Angelic). Align can apply either to characters or to equipment. For example, if an angelic player attempts to wield an anti-good weapon, it will repel the player and fall off immediately. Enchanting changes the alignment of an object to favor the alignment of the enchanter. It does not normally remove alignments that oppose the alignment of the enchanter. A player's alignment is changed by killing mobs. Killing a good mob will move your alignment towards evil, whereas killing a bad one will move your alignment towards good.
A good way to "fix" your align if you are evil is to portal to Crazy Kobold at Trials Of Zin. This is a tower with a large number of extremely wimpy evil level 3 mobs. A single cast of Burning Hands is enough to take them out.