VATICAN CITY (CNS) -- Bitter or boring evangelizers will not help the Gospel or the Catholic Church, Pope Francis said.

The church and the Gospel will only "move forward with evangelizers (who are) joyful, full of life," the pope said Jan. 28.

Christians must not be afraid or embarrassed to express the true joy that comes from having received the Word of God, the pope said at morning Mass in the chapel of the Domus Sanctae Marthae.

The pope focused his homily on the day's first reading from the Second Book of Samuel, which describes the festive and joyous atmosphere that comes with the return of the ark of God.

The people celebrate, the pope said, because God is with them and even King David dances "before the Lord with abandon."

David loves the Lord and "expresses his joy without shame. It is the spiritual joy of the encounter with the Lord," Pope Francis said. David does not think a king should be apart or distant from his people and takes part unabashedly in the festivities.

However, David's wife, Michal, was angered and embarrassed by his dancing and criticized him for behaving like "a commoner" and not like a king should, the pope said.

She represents the disdain some feel against genuine religious sentiments, "the spontaneity of joy with the Lord," he said.

God punishes Michal by having her remain childless, which can be interpreted as indicating "when a Christian is without joy, that Christian is not fruitful. When joy is missing from our heart, there will be no fruit," he said.

The church and the Gospel "will not go forward with boring, bitter evangelizers," Pope Francis said.

Evangelizers must not be like Michal, and not be "Christians imprisoned by formality," he said.

They must be full of the life and joy that comes from being Christian and able to celebrate without embarrassment, he added.