The pastor of the London church that Sir Keir Starmer apologised for visiting says he is "disturbed" by the Labour leader's comments.
Pastor Agu Irukwu told Premier that he had always admired Britain's "promotion of strong values, including fairness and justice" but it appeared these were now being undermined.
He added that the backlash over Sir Keir's Good Friday visit had been "upsetting", falling as it did over Easter, and that some of the responses were "possibly criminal".
"Over the past 48 hours, I have been disturbed to see these values eroded, especially in the courtroom of social media; we have felt prosecuted, judged, and sentenced unfairly," he said.
"Some of the language that has been directed at us can only be described as vile, abusive, hateful, and possibly criminal.
"It is tantamount to cyberbullying and the timing of this attack during Easter, one of the most important events in the Christian calendar, was particularly upsetting for us as a congregation.
"But Easter is also a time of forgiveness, hope and reconciliation, so we are really keen that despite all that has happened, this can still be a gospel moment."
Sir Keir visited the church to see its pop-up vaccination centre. He then posted a video clip of the visit in which he praised the church for all the good it is doing.
But when LGBT+ members of the Labour party expressed their anger over the visit because of the church's stance on marriage and sexuality, the video was pulled and replaced with an apology in which Sir Keir said it had been a "mistake" to go to the church.
Pastor Irukwu insisted that the church was not "anti-anyone". He also said it does not engage in conversion therapy but does provide "appropriate pastoral support, including prayer, to all our members, whatever life situations or circumstances they find themselves in".
"This is consistent with the basic fundamentals of freedom of speech and freedom of religion and the government's current position," he said.
He added his concerns for other churches and Christians who take a similarly conservative view of marriage and sexuality.
"There is an increasing atmosphere of bullying and intimidation which is a cause for concern, but we do not take our lead from politicians and others. Easter is a constant reminder that Jesus is victorious and our hope is found in him," he said.