A group of 63 ex-Catholic priests in the US state of Washington are due to announce their support for Referendum 74, the vote on equal marriage in the state, which will take place next month.

In a collective statement, the 63 ex-priests, who together have over 800 years of experience in the profession, said:

“We are uneasy with the aggressive efforts of Catholic bishops to oppose [equal marriage] and want to support the 71 percent of Catholics (Public Religion Research Institute) who support civil marriage for gays as a valid Catholic position.”

Pat Callahan, who organised the statement, and who was a Catholic priest for 15 years, said: “This is the first public action we’ve taken.”

An example of the “aggressive efforts” of bishops in Washington opposed to the idea of equal marriage is Bishop Joseph J. Tyson, of the Diocese of Yakima, who told his 41 parishes that equal marriage “jeopardises freedom rather than expands it” and “endangers our religious liberty and the rights of conscience,” he said in his latest pastoral letter.

“Once marriage is redefined as a genderless contract, it will become legally discriminatory for public and private institutions such as schools to promote the unique meaning of marriage…This law will challenge our right to educate about the unique value of children being raised by his or her own mother and father in a stable home,” Tyson wrote.

“Although our surrounding popular culture may define human identity by the terms ‘gay’ and ‘straight,’ our church has a deeper and more accurate understanding of human identity based on male and female — sexual difference,” he argued.

“I opened this letter with a wedding picture of my parents,” he wrote. “I close by asking you to consider what kind of picture of marriage you desire to give to the next generation. If you and I don’t uphold marriage as the union of a man and a woman, who will?” said Tyson.

Catholics for Marriage Equality, a pro-marriage equality group, which “promotes the freedom for all loving couples to be included in civil marriage”, responded to such opposition, saying:

“We are shocked when we read the language and examples used by our bishops to incite fear in our Catholic brothers and sisters if Referendum 74 passes. The message of Jesus is love and compassion, not fear.”

Religious groups in the state are split over the vote, but a poll last week, showed voter support for equal marriage in the referendum at 57%.

Maine and Maryland will also be voting on marriage equality on November 6. At the same time, Minnesota voters will choose whether to make a constitutional amendment which would define marriage as only between one man and one woman.