• Catholics now attend church at the same rate of Protestants.
• The greatest drop in attendance for Catholics occurred between 1955 and 1975.
• Attendance for Catholics has leveled out over the last decade.

Over the past six decades, church attendance for Catholics in America has gradually declined and now equals the attendance level of Protestants, according to a Gallup report released last week.

The data showed Catholic church attendance has declined from 75 percent in 1955 to 45 percent in the middle of the current decade, while Protestant church attendance went from 42 percent to 45 percent in the same time frame.

The decline in church attendance for Catholics was sharpest from 1955 to 1975 with attendance dropping 21 percentage points, according to the report. Since then, church attendance has dropped 4 percentage points per decade through the mid-1990s, according to the report.

Susan Wood, chair of Marquette's theology department, said it is interesting that the number of those who call themselves Catholic has not declined. They are willing to affiliate themselves with the Church because they find religious value in it, she said.

The report reviewed Gallup historical data to look for trends, said Lydia Saad, senior editor of the report. If the goal for churches is to bring more people back to mass, it is good to understand why they left, she said.

They can learn why they left by when they left, Saad said.

Between 1995 and 2009, the number of Catholics who say they attend church has remained relatively unchanged, according to the report.

There have been a lot of assumptions that the publicity from the sex abuse scandals within the Catholic Church in 2002 and 2003 hurt attendance, Saad said. However, she said this explanation is not reflected in the report.

There are a multitude of reasons for this decline, including an increase in secularism in society and disappointment with church changes, said Patrick Carey, Marquette theology professor and the Rev. William J. Kelly, Chair in Catholic Theology.

People today are more individualistic and do not feel like they have the same obligation to attend as they used to, Wood said.

Saad said one of the stronger theories she has heard for the decline in church attendance for Catholics is that changes from the Second Vatican Council inadvertently weakened the belief that Catholics had to go to church.

There used to be a Church law requiring Catholics that were relatively faithful to go to church, Carey said. After the Second Vatican Council, the Church did not emphasize the law, he said.

Now people think they can be good Catholics without going to church all the time, Wood said.

A reason for the drastic decline from 1955 to 1975 offered by theologians is the cultural revolution of the 1960s, according to the report.

Saad said the cultural revolution does not fully explain the decrease because Protestant church attendance did not decline.

The decline in attendance for Catholics is related to a decline in the sense of participation in Catholic communities, she said.

"When people don't attend regularly it erodes their sense of Christian community," Wood said.

History has shown that it is difficult to predict what will happen with church attendance, Carey said. There are cycles of high and low activity in the church and right now we are in a cycle of low activity, he said.