If there is one thing that the San Bernardino mass shooting confirmed, it's that radical Islam is a threat to the United States and its citizens, according to evangelist Franklin Graham.

"It's confirmed — San Bernardino shooter Syed Rizwan Farook was a devout Muslim. Friends say he had memorised the Quran. The headlines say Farook and his wife were a couple 'bent on jihad,'" Graham writes on his Facebook page.

However, he could not understand why President Barack Obama and his administration are still trying to blame this incident on gun control when "it was caused by hate-filled hearts intent on killing infidels in the name of Islam."

"Take away the guns and this couple would've still slaughtered innocent civilians," he continues. "Their apartment was a bomb-making factory! It's happened in France and it's happening here. ISIS has warned us that more attacks like this are going to follow. Next time it could be a mall or a school, but until our politicians understand and admit the threat of radical Islam we're going to have more of these horrible acts of violence."

Graham added that Farook's wife, Tafsheen Malik was allowed into America on a "K-1" fiancé visa. And according to recent report, she even pledged allegiance to the ISIS chief Abu Bakr Baghdadi before the massacre.

A very concerned Graham made a plea to Obama: "Mr. President, we don't need more gun control — we need border patrol. No Muslims should be allowed into this country until there's a process in place to fully vet them. We've got to turn away those who could potentially pose a threat until this war with radical Islam is over."

Graham asked fellow Christians to pray for the family members of the victims in the San Bernardino shooting, and he is also praying that America's current and future leaders will make the right decisions concerning radical Islam.