As Europe grapples with its biggest migrant crisis in recent history, Hollywood celebrities are rallying to raise awareness on the issue and are lashing out at calls to turn away refugees.This month, Oscar-winning actress Susan Sarandon became the latest star to visit the frontlines of the crisis, arriving on the Greek island of Lesbos, where she is spending her Christmas holiday to help the refugees who are arriving daily while writing about her experience for the Huffington Post and RYOT.org, a virtual reality news company."I hope that I can make it possible for them (the refugees) to have a voice so we can understand them," she wrote in one post. "Understand that 'these people' are just like us, wanting to keep their children safe, wanting them to have a future." Sarandon's support and that of other celebrities comes against the backdrop of inflammatory remarks from within the United States, where leading Republican presidential candidates and various politicians have made calls to prevent Muslims or Syrian refugees from entering the country.Actor Mandy Patinkin, who plays the CIA operative Saul Berenson on the hit television series "Homeland," also visited Lesbos earlier this month, saying that such rhetoric only fans the flames of intolerance. "This fear-mongering and hatred that's spread by people running for the office of president of United States is so misguided," he said in an appearance on the popular "Late Show" with Stephen Colbert. "It is important that we open our arms and our hearts to refugees that are fleeing a horrifying situation."Actor Edward Norton has also spoken out about the migrant crisis and raised nearly $460,000 on behalf of a Syrian refugee whose story prompted him to take action. The Syrian man, a scientist who lost seven members of his family in a bombing two years ago including his wife and a daughter, was featured on the website "Humans of New York" earlier this month. "I saw this story on one of my favorite sites, 'Humans of New York,' and it moved me to tears," said Norton, who has starred in films which include "The Incredible Hulk," "Fight Club" and the Oscar-winning dark comedy, "Birdman." "Let's reject the 'anti-human' voices that tell us to fear refugees and show this man and his family what Americans are really made of," he added.British actor David Morrissey, best known for his role in the popular zombie series, "The Walking Dead," said that it is essential for the world to respond to the crisis. "We can't turn a blind eye to this," said Morrissey after his trip to Lesbos this summer with the UN Refugee Agency (UNHCR). "We need to reach out, to help, as we would want people to reach out and help us."According to the UNHCR, more than one million migrants and refugees have reached Europe this year, including 970,000 who made the dangerous journey across the Mediterranean. U.S. President Barack Obama has pledged to take in 10,000 Syrian refugees over the course of the next year, five times the number the U.S. has taken in since 2012.