It follows the election campaign suspension put in placer after the Manchester terror attack.
Speaking during News Hour, Jonathan Arnott said that the party's referendum policy will give Christians an opportunity to change things linked with moral issues such as the death penalty.
He said: "You could say the same on a range of moral issues which might impact a lot of Christians. You could say the same about issues like abortion; you can say the say about issues like euthanasia.
"One of Ukip's policies is that if enough people want to change the law, on a particular moral issue, whether that's a left wing issue, whether that's a right wing issue, that they should be able to if they get enough signatures on a petition."
Arnott said that the manifesto, which was launched less than an hour before the national silence to remember the victims of the Manchester Arena bombing, states that the public would be able to call a referendum on different issues.
Local campaigns have also resumed but Labour, the Conservatives and the Liberal Democrats have said their national campaigning will not begin again until Friday.
Other key policies in the Ukip manifesto include an extra £11 billion a year for the NHS and social care by the end of the next parliament, funded by cuts in foreign aid.
They also include a pledge not to raise taxes, abolish the House of Lords, remove VAT on takeaways and backs a previous pledge to ban the wearing of burqas.
Listen to Jonathan Arnott speaking with Premier's Eno Adeogun:
