The Prosecutor General has filed charges against MP Päivi Räsänen (CD). She is accused of three counts of incitements against a minority group.
Räsänen was interior minister between 2011-15, and chair of the Christian Democratic Party from 2004 to 2015.
The charges filed on Thursday are based on three sets of issues.
One concerns Räsänen's writings on the websites of the Luther Foundation Finland, a conservative reform movement, and the Evangelical Lutheran Mission Diocese of Finland.
The other two charges relate to Räsänen's publications and statements on Twitter, Instagram, Facebook and on an Yle Puhe radio programme.
According to the Prosecutor General, the statements are derogatory and discriminatory against homosexuals and violate their equality and dignity. Thus, they overstep the boundaries of freedom of speech and religion and are likely to fuel intolerance, contempt and hatred.
Another preliminary investigation was dropped by the Prosecutor General. It was related to Räsänen's statements on commercial broadcaster MTV's Yökylä programme. The Prosecutor General decided that while she made a derogatory statement about homosexuality on the programme, it was a minor offence.
Räsänen cites Bible teachings
Räsänen said that the Prosecutor General's decision was surprising, and even shocking.
"I do not consider myself guilty of threatening, slandering or insulting any group of people. These are all based on the Bible’s teachings on marriage and sexuality," she told Yle on Thursday.
According to Räsänen, it is basically a question of whether a belief based on the traditional teachings of the Bible and the Christian churches can be expressed in Finland. She insisted that she supports the dignity and human rights of homosexuals.
EDIT 4.6.2021: An earlier version of this story incorrectly named the Evangelical Lutheran Mission Diocese of Finland, and suggested that it operated under the auspices of the state-supported Evangelical Lutheran Church of Finland. That is not the case.