Instead of their wedding programs, Stephen and Andrew were sent "hateful" pamphlets.

On the eve of their wedding, Stephen Heasley and Andrew Borg opened up the package they expected to contain their wedding programs.

Instead, the Aussie couple were horrified to find “hateful, discriminatory” religious pamphlets, sent in their place by printing company, Vistaprint, the New York Post reports.

In place of 100 copies of custom-designed programs that were supposed to include lyrics to their wedding song, ‘Treasure’ by Above and Beyond – the couple received pamphlets that warned “Satan entices your flesh with evil desires”.

Now, the couple is suing Vistaprint for an unspecified amount over what they claim was a deliberate attempt to threaten them with anti-gay religious propaganda about sin and temptation.

Andrew and Stephen, who were wed in Pennsylvania in September, said in a statement their goal was to "hold Vistaprint accountable for the harm they have caused …and to send a message that there will be consequences for acts of hate perpetrated against others".

Their suit was lodged in Massachusetts, where the Dutch company's US headquarters are based, on Tuesday. According to the New York Post, their suit also targets a 'John Doe' - the employee or outside person responsible for the switch.

The complaint documents say the pamphlets, titled 'Understanding Temptation: Fight the good fight of the faith' had been sent to "threaten and attack" the men because they are gay.

LISTEN: We take a look back at the very long road that led to Australia finally legalising marriage equality. (Post continues.)

In addition to being "emotionally devastated," the couple then had to print their own programs immediately at an extra cost.

Meanwhile, Vistaprint spokespeople said the company was investigating the sabotage and sympathised with the couple.

"We share in this couple's outrage. Vistaprint in no way condones — and does not tolerate — discrimination against any of our customers based on their race, religion, gender or sexual orientation," CEO Trynka Shineman and Founder Robert Keane said.

Shineman said the company's investigation suggested that it wasn't a Vistaprint employee responsible, but a third-party partner.