A new study conducted by Barna Research as found that the number of American Christians who believe that sharing their faith is necessary has dropped by 25 percent in a quarter of a century.

The findings, released on May 15, has shown that 64 percent of the respondents agreed with the statement "Every Christian has a responsibility to share their faith." In contrast, 89 percent agreed with the statement in 1993.

The poll results have also shown an increase in Christians who believe that "converting people to Christianity is the job of the local church" and not the responsibility of an individual believer.

Twenty-nine percent of Christians agreed with the statement today, compared to just 10 percent in 1993.

Forty-seven percent of Christians today believe that proselytizing is more effective when they already have a relationship with the other person. As many as 44 percent said that they would avoid a conversation about religion if they knew that they would be rejected.

Twenty-eight percent of Christians today said they were unsure whether "most non-Christians have no interest in hearing about Jesus," compared to just five percent in 1993.

The study also found that Christians today are less likely to quote Bible passages or challenge another person's beliefs when sharing their faith.

As many as 59 percent of Christians in 1993 say they quote Bible verses in their attempts to convert another person to Christianity, compared to only 37 percent today.

Forty-three percent of Christians in 1993 said they challenge other people about their beliefs during an evangelism attempt, compared to just 24 percent of the respondents today.

The researchers believe that Christians are becoming less interested in evangelizing because of several social factors.

"So what's happening here? Why are Christians so reluctant to talk about their faith? The overarching cultural trends of secularism, relativism, pluralism and the digital age are contributing to a society that is less interested in religion and that has marginalized the place of spirituality in everyday life," said Roxanne Stone, editor in chief at Barna Group.

"As a result, Christians in America today have to live in the tension between Jesus' commands to tell others the good news and growing cultural taboos against proselytizing—a core part of Christianity from its origins and, many practicing Christians believe, is essential for the salvation of their listeners," she continued.

A separate Barna study released in March has shown that a little more than half of Christians in the U.S. are not familiar with the term the "Great Commission."

The findings of the study showed that 51 percent of churchgoers had never heard of the term, while 25 percent said that they have heard about it, but they cannot remember what it is. Only 17 percent said they were familiar of the Biblical passage associated with the term.