Dr. Brian Lee (you know, the pastor of the "other" Christ Reformed Church in DC) has a great essay in the Federalist addressing the canonization of two popes to sainthood (Canonization and Celebrity Culture).
The church isn’t just susceptible to celebrity culture; it generates it. American evangelicalism has more than its share of celebrity pastors. George Whitefield, Jonathan Edwards, Charles Finney, Billy Sunday, Aimee Semple McPherson have all been among the most famous and most recognizable figures of their day. Billy Graham even wears something of an untouchable papal tiara in his fading glory — What? He criticized Billy Graham?
But our religious pop culture can’t hold a candle to Rome’s pope culture and endless cataloguing of saints — somewhere between 921 and 10,000, depending on who is counting.
And here is the twofold nub of the offense. First, the canonization of saints encourages and indeed validates the veneration and invocation of creatures, not the Creator, trading on their power and goodness. It does so on the basis of their personal merits, howsoever fueled by the grace of God. God, however, hears our prayers because he alone is omniscient and good. But the saints, even in glory, are still mere men. What gives us reason to believe they can hear us when we cry out to them?