One of the most exciting developments in the papacy of Francis to date is that he's already mentioned the Devil several times: At his first papal Mass in the Sistine Chapel, during the homily to the cardinal electors:
"Whoever does not pray to God, prays to the devil." He continued: "When one does not profess Jesus Christ, one professes the worldliness of the devil."
Two days later to a gathering of the cardinals he emplored that they "not cede to the bitterness and pessimism that the devil offers us every day."
When struggling to stop the Argentine government from legalizing same-sex "marriage," he said:
Let's not be naive: This is not a simple political fight; it is a destructive proposal to God's plan. This is not a mere legislative proposal (that's just its form), but a move by the father of lies that seeks to confuse and deceive the children of God ... Let's look to St. Joseph, Mary, and the Child to ask fervently that they defend the Argentine family in this moment ... May they support, defend, and accompany us in this war of God.
A pope who openly and repeatedly speaks about the language of the devil, the father of lies, the war against God, and prayer to the Holy Family as a way to combat it clearly understands the fullness of the Church’s teaching on spiritual combat! The Holy Father thus seriously asserts again that sin exists, that it's more than a matter of mere human weaknesses and errors, that the whole of the old Christian drama as a contest between God and Satan is still the center of the Faith — and the reason that the Church exists — just may have something fresh to say to the world. Read more on the topic here.