PHILADELPHIA (CBS) — Ash Wednesday marks the official start of the 40-day season of Lent for Christians.

Hundreds of the faithful gathered for mass in the Cathedral Basilica of Saints Peter and Paul on the parkway.

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Ashes were placed on their foreheads with an admonition to repent and believe in the Gospel.

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In his homily during the mass, Archbishop Charles Chaput reminded the flock that they are engaged in spiritual warfare.

“We are in battle, all of us, against as this prayer says the spiritual forces of evil,” Chaput said. “Beginning where? In our hearts, right? I mean that’s the source of all evil in the world is our hearts, but also in the world around us.”

Chaput says Christians are called to prayer, fasting and “almsgiving.”

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He says of the three, the one that is easiest, “almsgiving,” seems to fall by the wayside for too many during Lent and beyond.