Freedom of religion or belief is increasingly under threat around the world. The harrowing video released last month of the apparent murder of Ethiopian Christians by ISIL in Libya, was just the latest appalling reminder of this. It was a chilling echo of the equally horrific murder of 21 Egyptian Christians in Libya in February, and it follows the regular reports of mass murder, forced conversions and sexual slavery that has been visited upon minority religious communities in Iraq and Syria.

The persecution of religious minorities is most acute, and has been most in the headlines, in Libya and Syria, but there are many other locations around the world where religious freedom is violated on a daily basis. And it is not only Christians who are affected, though they are – both in number and in geographical scale – the most persecuted. Yazidis in Iraq, Ahmadiyya Muslims in Pakistan and Indonesia, Bahai's in Iran, Rohingya and other Muslim minorities in Burma, are among the many non-Christians who also face serious discrimination.

Since 2010, promoting and protecting freedom of religion or belief, and supporting those facing persecution, has been a priority for this government. That is why we created the Foreign Office's Advisory Group on Freedom of Religion or Belief to ensure we have the best advice available on practical ways to defend the right to freedom of religion or belief. And it is why we put our principles into practice, taking action to get vital humanitarian aid to those fleeing persecution who were stranded on Mount Sinjar, or through funding grassroots reconciliation between different communities in Iraq.

I and my ministerial team have engaged tirelessly with governments and leaders across the globe, lobbying on behalf of oppressed religious minority communities and intervening to save individuals suffering persecution for their beliefs.

As we have stated clearly in our election manifesto, the next Conservative government will continue to stand up for the freedom of people of all religions and none. And, as a country with a generous overseas aid budget, we will continue to use that money to help prevent the conflict, instability and resource pressures that are so often among the drivers of religious persecution.

Just over 200 years ago, a great parliamentarian – William Wilberforce – led the campaign for the abolition of slavery. He succeeded in abolishing the transatlantic slave trade, but two centuries on we face new battles over injustice. Modern slavery in its various forms is one. Threats to the fundamental right to freedom of religion or belief is another. We simply cannot stand by while people are executed, abused, discriminated against or enslaved because of their faith or beliefs; and we will not.

A Conservative government will continue to make the promotion of freedom of religion or belief a key part of our foreign policy, by using all the tools at our disposal to counter religious extremism, promote inter-faith harmony and develop international mechanisms to defend effectively one of the most basic of human rights: the right to believe and to practice your beliefs without fear and in peace. We surely owe it to those Christians who have been so brutally murdered in recent months for their religion to ensure that those who killed them do not succeed in their objective to silence the Christian voice and to demonstrate beyond doubt that they did not die in vain.

Philip Hammond is the Secretary of State for Foreign and Commonwealth Affairs. Before parliament was dissolved he was the MP for Runnymede and Weybridge, where he is standing again.