A politicized issue is a social, economic, theological, spiritual, medical or legal issue which has become a political issue, as a result of deliberate action or otherwise, whereby people become politically active over that issue.
A contemporary example is abortion, an emotive and moral issue which has become a highly contentious legal and political issue in many countries. Terminology relating to such issues often takes the form of loaded language which contrasts with the pejorative terms used in reference to opponents. For example, those who think that abortion should be a legal medical option describe their views as pro-choice, and may label their opponents as "woman haters" or "right wing fundamentalists". Similarly, those opposed to legalized abortion describe their views as pro-life, and may label their opponents as "baby killers" or "murderers".
Heavily politicized issues are often called "hot button issues" because almost any position taken is sure to please one group of people and offend another. Politically active people and organizations will often employ a 'litmus test' to evaluate a candidate. For example, a candidate for political office who shares the same view on abortion as a political organization may receive their endorsement regardless of the candidates views on other subjects.
Sometimes the term "politicized" itself becomes a negative label. A group holding one opinion on an issue will sometimes accuse their opposition of "politicizing the issue". The implication is that they are honestly dealing with the issue on the merits while the opposition is bringing the issue up purely for political gain.