SASTIN, Slovakia, Sept 15 (Reuters) - Pope Francis wrapped up on Wednesday his trip to Hungary and Slovakia, during which he urged the predominantly Catholic countries not to close up and to avoid using religion for politics. On the last day of his journey, Francis presided over an open air Mass for more than 50,000 people at a national shrine in Western Slovakia, traditionally popular with women in difficult marriages. The shrine of Our Lady of the Seven Sorrows in Sastin, near the borders with the Czech Republic and Austria, has its origins in the 16th century when, according to a legend, the wife of a count who mistreated her prayed to the Madonna to change him. Once, when he threw her out of their carriage after a quarrel, she prayed on that spot and promised to commission a statue in Madonna"s honour if she transformed the husband. As she walked home, her husband turned the carriage, came back for her, and, crying, asked his wife for forgiveness. The wooden statue, known as the Sorrowful Madonna, and which measures 85 cm by 91 cm, was brought out of the shrine and placed near the altar where the pope held the last event of his trip before his return to Rome. Today the Sastin shrine collects online requests for prayers, mostly concerning family issues such as marriage troubles. At the cross above the altar, two beams from a church destroyed by a tornado that ripped through neighbouring Czech Republic in June were placed. Francis, 84, who has appeared in good shape throughout the journey despite his July surgery, thanked the organisers and the faithful at the conclusion of the Mass. During his four-day journey, the pope warned against exploiting religion for politics, and he called out prejudice and discrimination as he visited a Holocaust memorial and stopped at an impoverished Roma community.