Rev Franklin Graham, son of popular evangelist Billy Graham, has told Islamic State militants that God loves them and is willing to forgive them.

He offered this message of love to the militants despite expressing anger and disappointment towards the White House for "seemingly continuing to protect Islam" and for refusing to call the 21 beheaded martyrs as Christians.

"I am perplexed as to why our president will not acknowledge the truth and call Islamic extremism what it is," he wrote in his Facebook page. "In a statement the White House even called the 21 Christians who were beheaded 'Egyptian citizens,' refusing to identify them as Christians. The truth is — their barbaric murderers openly killed them because they were 'people of the cross.'"

But during an interview with Fox News' Greta Van Susteren, Graham offered a message of hope and reconciliation for the members of the terrorist organisation. He told them that despite all the horrible things they have done, God's love can save them.

"God loves you and God is willing to forgive you, but you've got to be willing to confess your sin to Him and ask Him for forgiveness and by faith invite His Son Jesus Christ into your heart. If you do that, God will forgive you for what you have done and God will heal your heart and He'll invite you to be with Him for eternity in Heaven," he urged them.

He also told Muslims around the world that God loves them too, and that they do not need to have their heads cut off or die in holy wars in order to receive God's approval.

"Mohammed is dead and buried in Medinah. Jesus Christ is alive and He is sitting at the right hand of God the Father in Heaven. Who do you want to follow, the dead or the living?" he asked.