US President Barack Obama has this week spoken out about his "biggest frustration" – the failure of Washington to put an end to violent gun crime in America.

According to advocacy group Everytown for Gun Safety, there have been a total of 74 school shootings across the US since the tragedy at Sandy Hook – one every seven days.

One student was killed and several more injured by a lone gunman at Seattle Pacific University (SPU) on June 5, and just this week another student died after being shot by a gunman who then turned the pistol on himself at Reynolds High School in Troutdale, Oregon on Tuesday.

These incidents have once again triggered outrage from those campaigning for stricter gun laws, and President Obama – who committed to tightening arms controls following Sandy Hook in 2012 – has now expressed his regret that no new laws have yet been passed by Congress.

"I will tell you, I have been in Washington for a while now. Most things don't surprise me. The fact that 20 6-year-olds were gunned down in the most violent fashion possible and this town couldn't do anything about it was stunning to me," Obama said from the White House on Tuesday

"A lot of people will say, 'It's a mental health problem, it's not a gun problem'. The United States does not have a monopoly on crazy people. It's not the only country that has psychosis, and yet we kill each other in these mass shootings at rates that are exponentially higher than anyone else," he continued.

"Well, what's the difference? The difference is that these guys can stack up a bunch of ammunition in their houses, and that's sort of par for the course."

Despite his office, Obama contended that he is unable to effect real transformation unless regular American people who want to see an end to the violence make their voices heard.

"The only thing that is going to change is public opinion. If public opinion does not demand change in Congress, it will not change," he declared.

"The country has to do some soul searching about this. This is becoming the norm and we take it for granted in ways that, as a parent, are terrifying to me...Right now it's not even possible to get even the mildest restrictions through Congress, and we should be ashamed of that."

The right to keep and bear arms is affirmed by the Second Amendment in the US Constitution, and pro-gun groups across the US have been lobbying for years to protect what they see as a fundamental human right.

American conservative activist Samuel Wurzelbacher, known to most as 'Joe the Plumber', even penned an open letter to the families of those caught up in 22-year-old Elliot Roger's killing spree at the University of California on 23 May, in which he contends, "your dead kids don't trump my Constitutional rights".

"As a father, husband and a man, it is my responsibility to protect my family. I will stand up for that right vehemently. Please believe me, as a father I share your grief and I will pray for you and your family, as I do whenever I hear about senseless tragedies such as this," Wurzelbacher wrote.

"We still have the Right to Bear Arms and I intend to continue to speak out for that right, and against those who would restrict it – even in the face of this horrible incident by this sad and insane individual."

This pro-gun movement has become associated particularly with the Christian Right; ask anyone to conjure up an image of a fundamental American Christian and it's likely to be a NRA-loving, Bible-wielding, bearded hillbilly with a penchant for guns – think Duck Dynasty's Robertson family. Si Robertson famously once told Men's Journal: "It ain't gun control we need, it's sin control".

In an article for the Huffington Post, however, blogger and theological seminary student David Michael Macfarlane writes that "Gun violence affronts the heart of Christianity".

"It is my faith that leads me to view human lives as precious and deserving of protection," Macfarlane contends.

"The central narrative of Christianity follows a saviour who sacrificed his own life and commanded people to love their enemies, including, surely, those who break into homes to steal televisions. How have so many people forgotten this -- inverted this, in fact?

"Somehow religious folk especially have been duped into believing that to conceal a gun in a purse or jacket is the mark of a good citizen, when in fact it is an act of absolute cowardice and disregard for the beauty and value of our fellow humans."

Macfarlane goes on to assert that Christians must "stand up and call this destruction of lives evil", and in doing so "affirm...the value of every person on this planet".

"I don't want a sermon or a prayer vigil. I don't want an article written about the nature of sin," he concludes.

"I want members of the Christian Right to look at their Bibles and admit that humans shouldn't kill each other or carry around handguns manufactured for no other purpose.

"I want the politicians who invoke Jesus the most to understand turning the other cheek invalidates their fantasies of an armed populace.

"I want American Christians to contemplate the stunning and grave declaration that every man, woman and child is fearfully and wonderfully made, because that might stop even one person from shooting his family or teacher or himself, which would be enough."

SPU Student John Meis, who has been hailed as a hero after overpowering gunman Aaron Ybarra, backs this up in a heartfelt letter expressing that forgiveness and mercy – though difficult – are the correct Christian response to tragedies such as that of June 5.

"I would encourage that hate be met with love," he writes.

"When I came face to face with the attacker, God gave me the eyes to see that he was not a fearless monster, but a very sad and troubled young man.

"While I cannot at this time find it within me to forgive his crime, I truly desire that he will find the grace of God and the forgiveness of our community."

Watch Obama's speech below: