The Vatican announced on Thursday that the competent dicastery in the Vatican considered his execution on 17 April 1944 to be a martyr's death.
This means that nothing stands in the way of his beatification in the near future or a possible canonisation at a later date.
The priest, who came from Schopfheim in Baden, became a pacifist after his experiences as a military chaplain in the First World War and founded several pacifist groups.
As early as 1933, he emphasised the contrast between the Church and National Socialism in a memorandum. He was arrested by the Gestapo for the first time in 1934 and several times thereafter.
On 14 October 1943, he was sentenced to death by the People's Court under judge Roland Freisler in a show trial; the execution took place in Brandenburg an der Havel.
In 1994, a square in the Berlin district of Wedding was named after Metzger. In 1997, the Berlin District Court posthumously cancelled the death sentence.
The beatification process for Metzger was opened on 8 May 2006 by the then Archbishop of Freiburg, Robert Zollitsch.
He described Metzger as a "prophetic martyr".