POLITICS
While Catholics can legitimately have diverse views on many issues related to finances and politics, we cannot compromise on issues that are grounded upon moral principles because they are established by God. When the Church teaches morality it is Christ teaching through her.
Why government can and in many cases should prohibit moral evils. http://www.catholicculture.org/commentary/otc.cfm?id=1018
1- Natural law contains moral truths that we can understand through reason.
2-Adherence to the natural law, unlike adherence to truths known only by Faith, is morally binding on all persons and may be justly required of them by government when necessary for the common good;
An example of this is laws on abortion. We know its morally wrong not just because of religious faith but by reason through natural law.
3-Because of natural law, it is justified for government prohibit and punish naturally recognized evils such as fraud, theft, assault, sexual abuse, and murder; These are not just religious beliefs but truth that can be understood by reason.
4-However, it is not always best for government to prohibit and punish some particular violations of the natural law;
5-Whether or not to do so is a matter of the legitimate purposes of government and prudence, which is necessary to determine whether government can act effectively and without doing more harm than good;
6-Government, therefore, may choose not to restrict or punish some moral evils which are otherwise within its legitimate scope (For example, contraception or sex outside of marriage);
But gov. must protect the fundamental rights of its citizens and that includes the right to life. Protection of human life is the first purpose of government.
7- Government must never, under no circumstance, encourage or promote any moral evil, give them the status of rights, or coerce people into supporting them.
