LUND, Sweden (AP) — Pope Francis hopes that his upcoming visit to Sweden on the 500th anniversary of the Protestant Reformation will help in uniting Christians.

The pontiff, who is heading to the largely Lutheran country in Scandinavia, tweeted Sunday: "I ask you to please pray that my journey to Sweden might contribute to the unity of all Christians."

The pope's two-day visit on the celebration that marks Martin Luther's challenge to the Catholic dogma is widely seen as the Vatican's efforts to mend ties with other Christians.

After his arrival Monday, Pope Francis will meet the Swedish prime minister, members of the royal family and participates in an ecumenical prayer service at the Lutheran cathedral in Lund, southern Sweden. Joining him is the head of the Lutheran World Federation, Bishop Munib Younan.