My opinion, as briefly as I am capable of stating it:
Rick Santorum, a Big Government, status quo, Washington insider, socialist and phony conservative no better than the likes of Bush, McCain, Gingrich, Romney and all the rest; Santorum voted to increase funds to Planned Parenthood, endorsed the most pro-abortion Republican Senator in Congress, is a fanatic warhawk for Israel and therefore fully endorses genocide and the continued rape of the Holy Land and all the slaughter of innocents throughout the Middle East...the man is UNFIT TO CALL HIMSELF A CATHOLIC, let alone a conservative, or fit to run the country.
Ron Paul, on the other hand, is unquestionably the MOST PRO-LIFE CANDIDATE RUNNING FOR PRESIDENT AS WELL AS THE MOST PRO-LIFE MAN IN ALL OF WASHINGTON, DC, who has NEVER voted to fund Planed Parenthood, or endorsed abortion which he correctly calls a violent act, who has consistently introduced/reintroduced the Sanctity of Life amendment which would AUTOMATICALLY REVERSE ROE VS. WADE, who refused to run as a libertarian because of his uncompromising pro-life conviction (he's only libertarian in the areas of economics and government, but this only means he's not perfect) and who is the most outspoken voice on the planet for PEACE (referring to the Prince of Peace as his inspiration and OUTDOING THE POPE, ALL THE BISHOPS AND EVEN OUR TRADITIONAL CATHOLIC CLERGY) in strong opposition to ENDLESS, SENSELESS, IMMORAL, UNJUST, UNCONSTITUTIONAL WARS with their weapons of mass destruction and all the pain and death and war profiteering which the Church emphatically condemns (see the book I co-authored with Tom Gabriele, "Modern Wars in the Light of Catholic Teaching").
My advice, for whatever it's worth: Every Catholic, Christian and patriot of conscience should vote for Ron Paul. And if he should not become the Republican Party's choice, WRITE HIS NAME ON THE BALLOT (perfectly legal and it sends a real message to the Powers That Be) rather than endanger your soul by casting a vote for any of the other PRO-DEATH candidates - Santorum, Gingrich, Romney - they are all the same.
League of Christ the King, SSPX