A senior priest at the Vatican who was sacked when he revealed he is gay has condemned "the homophobic hate of the Church" in a letter to the Pope.

Poland-born Krzysztof Charamsa, 43, wrote: "Today, I side with the fantastic people who are homosexual, for centuries humiliated by a fanatical Church. I no longer accept the salvation that excludes – without any foundation whatsoever – a part of humanity."

A former high-ranking official with the Congregation for the Doctrine of the Faith, Father Charamsa wrote to the Pope outing himself on the eve of the three-week Synod on the Family.

In the letter to Pope Francis, only now released through the BBC, he described the feeling that prompted him to leap over the "imprisoning walls" of Church teaching.

He said the Church knows only how to persecute homosexuals. "The Church has excluded them as lepers, as if humankind were able to choose its own sexual orientation: heterosexual or homosexual."

The synod has just ended without any concessions regarding the language or teachings on homosexuality, to the disappointment of the LGBT community. The Catholic Church teaches that homosexuality is "ordered towards an intrinsic moral evil."

In the letter, written in Italian and obtained by BBC Radio 4's Today programme, Father Charamsa, who has a Catalan boyfriend, said that as a baptised Catholic, a priest and a theologian, he had wanted to serve the Church his whole life. 

"After a long and tormented period of discernment and prayer, in front of God and with full awareness of the gravity of the momet, I have taken the decision publicly to reject the violence of the Church towards homosexual, lesbian, bisexual, transsexual and intersexual people. As a man of homosexual orientation myself, I can no longer bear the homophobic hate of the Church, the exclusion, the marginalisation and the stigmatisation of people like me – continually offended in their dignity and with their human rights denied and defeated by this violent Church and its people."

He said homosexuals do not need the compassion promised by the Church.

"We are not the enemies, either of the Church or of the family, a misleading and offensive image that the Church has succeeded in creating," he wrote.

"We ask only to be respected in our dignity and in our rights as the human beings that we are. If the Church is so dull (stupid?), so incapable of reflection, so (slow to admit change?) in its knowledge of human beings... and if it cannot succeed in embracing those people, at the very least it should stop putting pressure on states and nations that do wish to respect the human right of homosexual people to enter into civil matrimony."

Charamsa called for all statements from the Holy See that are "offensive and violent" against homosexuals to be withdrawn and cancelled, and for "the obscene instructions of Benedict XVI" forbidding the admission to the priesthood of homosexuals to be annulled as well.

He also urged all gay cardinals, bishops and priests to have the courage to abandon "this insensitive, unfair and violent (brutal?) Church." He went on to describe the Church as "formed by shepherds without heart and without brain" and said priests and bishops should apologise for it.

"Some of them are with you in the Synod, with their language of hate, deprived of sensitivity, interested only in how to invade and subdue democratic governments, in how to steal, in how to appropriate the common good, in how to deny the fundamental rights of people," he added, admitting that he had gone through a long period of internal struggle to get to this point. 

"If the salvation offered by the Church doesn't respect the nature of homosexual people, I refuse that salvation. I refuse it on behalf of God, who has created us and who loves us as we are."

He said he fears for his mother, a woman of unshakeable faith. "I know what risks she runs in this brutal and insensitive Church, to which she has unconditionally dedicated her whole life. In Poland, many Catholics know how to be masters of hate, of stigmatisation and the exclusion of others, and of homophobia. My mother doesn't deserve to be offended by that inhuman Polish church."

Gay people have the right to a family life, even if the Church does not wish to bless it, Charamsa said, pleading for mercy. "We exist and we will always exist, even if your Church keeps on trying to reduce us to nothing, as it still does with divorced and remarried people."

He concluded: "I will do my best to help homosexual people to awaken the Catholic Church from its inhuman sleep, which has caused immeasurable suffering."