Politicians from the conservative Christian Democratic Union (CDU) and the liberal Free Democrats (FDP) told Tuesday's daily Bild newspaper it was unfair if regular attendants of church services couldn't find a seat at Christmas.
"I support making services on December 24 open only to those who pay their church tax," a member of the CDU board in the south-western state of Baden-Württemberg, Thomas Volk, told the mass-market daily. Germans pay church tax along with their income tax unless they opt out.
The head of the FDP's parliamentary group in Berlin, Martin Lindner, said it was intolerable that in the past, active members of church congregations - often the elderly - had been forced to stand through the Christmas service because the pews were full.
"Church tax payers should not be kept outside during such important services," he said. "Church members should be given tickets, for example, to give them priority seating."
Last year 246,000 people attended Protestant church services on Christmas Eve in the capital, versus an average of just 17,000 on a normal Sunday, daily Tagesspiegel reported on Sunday.
Scuffles broke out among churchgoers two Christmases ago at the Berlin Cathedral, the city's biggest church, over available seats. Last year the church distributed free tickets to members guaranteeing them a seat at the Christmas Eve service, and is doing the same this year.
But some church leaders say reserved spots in the pews send the wrong message. "We should not be giving the impression that there is a two-class society in the church," said Stefan Foerner, spokesman for Berlin's Roman Catholic Archbishop. "Jesus would not ask whether someone paid their church tax or is baptised."