As verbs the difference between sinning and abandoned

is that sinning is (sin) while abandoned is (abandon).

As a adjective abandoned is

self-abandoned, or given up to vice; immoral; extremely wicked, or sinning without restraint; irreclaimably wicked ; as, an abandoned villain {{defdate|first attested from 1350 to 1470}}{{reference-book | last =| first = | authorlink = | coauthors = | editor =brown, lesley | others = | title = the shorter oxford english dictionary | origdate = | origyear = 1933| origmonth = | url = | format = | accessdate = | accessyear = | accessmonth = | edition = 5th | date = | year =2003| month = | publisher =oxford university press | location =oxford, uk | language = | id = | doi = | isbn =978-0-19-860575-7 | lccn = | ol = | pages =2| chapter = | chapterurl = | quote =}}.