PROVIDENCE — Today is the only day of the year you can tell a practicing Christian by looking at his or her forehead.

Christians will seek out churches to mark the beginning of Lent with Ash Wednesday. Palm fronds from last year’s Palm Sunday — the Sunday before Easter in the Roman liturgy — are burned and the ashes imposed on the foreheads of those who believe in the divinity of Jesus Christ.

The Most Rev. Thomas J. Tobin, bishop of the Roman Catholic Diocese of Providence, will celebrate Mass at noon at the chapel at Our Lady of Fatima Hospital in North Providence. He will be assisted by the Rev. Robert E. Lacombe, the Rev. Robert A. Schaldone and the Rev. Varghese Thekkeattayil, who will concelebrate the Mass.

Ash Wednesday is the beginning of the Lenten season, which recalls Jesus’ 40-day fast in the wilderness, as described in Gospels of the New Testament.

It is a religious tradition that dates to 325 A.D. and the Council of Nicaea, according to the Rev. John Vidmar, a Providence College theology professor.

Ash Wednesday begins the observance of Lent, a time of self-examination, repentance, prayer, fasting and self-denial.

“It is like spring training in a way,” says Father Vidmar. “Psychologically, it prepares us for Easter and when Easter comes there is a physical relief as well as a psychological and spiritual renewal,” said Vidmar.

The number 40 is also deeply embedded in the Jewish tradition, says Father Vidmar. “In the Old Testament…floods lasted 40 days and the Jews spent 40 years of wandering.”

A generation or two ago, one easy way to tell the difference between a Catholic and a Protestant in New England was to see who had ashes on his or her forehead on Ash Wednesday. Catholics did and Protestants mostly did not.

That has changed over the past few years, with many Protestant churches imposing the ashes on members of their congregations.

“Years ago we didn’t make much out of Lent either,” says the Rev. Rebecca Spencer, senior minister at Central Congregational Church on the East Side of Providence. “I think now in Protestantism there is a heightened awareness of the importance of sacrament and ritual.

“Ashes are an ancient symbol of our humility and need for forgiveness,” says the Rev. Spencer. Ash Wednesday is also an important harbinger for the coming of Easter, the Rev. Spencer says, with its message of renewal and reminder that Christians believe that Jesus Christ died for the sins of humanity.

In an increasingly secular society where the incessant message of the modern media is about getting and spending, the Rev. Spencer says Protestant Christians have “a hunger” for tradition and the sacred.

The Rev. Spencer also noted that Ash Wednesday harkens to a time before the Protestant Reformation of the 1500s.

At Central Congregational, services are scheduled for 7:30 tonight. While some churches have Ash Wednesday services early in the day, the Rev. Spencer says her church waits until evening, because Jesus warned against showy displays of piety. “Beware of practicing your piety before others in order to be seen by” others, reads the Gospel according to Matthew, in the King James Version of the Bible.

At Central Congregational, the communion table is open to anyone who finds meaning in the life of Jesus Christ, the Rev. Spencer says.

The Rev. Jonathan Almond, minister at Mathewson Street United Methodist Church in downtown Providence, will officiate at services beginning at 9 a.m. Almond, too, remembers a time when Methodists did not have Ash Wednesday services.

Almond says that his denomination began celebrating beginning of Lent in the 1960s and 1970s as a result of the ecumenical religious movement and the Second Vatican Council (1962 to 1965) in the Catholic church. “We began to enjoy a sense of sacrament and began to highlight Lent and Ash Wednesday.”

The Second Vatican Council called for a renewal of Lent, recovering its ancient baptismal character.

This morning, the Rev. Almond said, he will read from the Prophet Joel, who issued a clarion call to return to the Lord “with fasting, and weeping and mourning.” Joel also reminds us that our God is “gracious and merciful….slow to anger, rich in kindness and relenting in punishment.”

Throughout the state today, Christians will flock to churches and will be reminded of their own mortality, hearing someone say a version of these words, “Remember that you are dust, and to dust you shall return.”

smackay@projo.com