Heiner Geissler was widely regarded during the 1980s as a modernizing force inside Germany's Christian Democrats (CDU), having been credited with shaping the party's foreign policy towards the Soviet Union, and also its social welfare programs.

However, he was never one to shy away from attacking his opponents.

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His accusation in 1983 that the Social Democrats (SPD) served as Moscow's "fifth column"  has become political folklore in Germany. That same year, while campaigning opposition to US missile bases in Europe during the federal election, he cited a famous quote from German novelist Bertolt Brecht in his rebuke of the SPD: "Those who don't know the truth are dummies, but those who know the truth and call it a lie are criminals."

Willy Brandt once accused him of being the "worst agitator since Goebbels," but Geissler always justified his remarks, saying that as secretary general he always needed to be a vanguard.

Despite becoming a major figure in the CDU, differing and increasingly left-leaning views eventually strained relations with then-Chancellor Helmut Kohl. Geissler was forced to resign as secretary general in 1989, but remained a member of the Bundestag until 2002 as a member of parliament for his home state Rhineland-Palatinate.

After ending his career in politics, Geissler became an outspoken critic of neoliberalism, even joining the anti-globalization movement Attac.

One of his last major public contributions saw him arbitrate heated collective bargaining disputes over the Stuttgart 21 high-speed rail project, mediating issues such as including relative costs and benefits for workers, which eventually lead to the project going ahead.

German Chancellor Angela Merkel paid tribute to Geissler, describing him as "intellectually outstanding, rhetorically brilliant, disputatious, confident and always people-orientated."

Merkel's chief of staff, Peter Altmaier (CDU), wrote on Twitter that Geissler had "shaped the Christian Democrats" into a party guided by social and ecological responsibility.

The CDU's regional chairman in North Rhine-Westphalia, Armin Laschet, described Geissler as "intellectually brilliant" and "one of our best."

German Foreign Minister Sigmar Gabriel, a member of the SPD posted on Twitter: "For his party and for many citizens of our country, Geissler was an influential political figure of the first few decades (after the war). German democracy benefited from his trenchant views on the Left party and the Social Democrats."

A social reformer

In his early political career as minister for labor and social affairs in Rhineland-Palatinate from 1967 to 1977, Geissler implemented the first law concerning kindergartens, and introduced the state's first welfare stations.

In his book Neue Soziale Frage (New Social Question), Geissler outlined his political vision for improving conditions for those whose welfare was not tied to an employer or represented by a trade union, namely pensioners, families and students.

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As CDU secretary general, Geissler paved the way for nationwide parental leave and was widely credited with helping form Germany's pension insurance program.

He also served in Kohl's cabinet from 1982 to 1985 as minister for youth, family and health.

Guide by Christian teachings

Geissler was born and raised Roman Catholic and stated that he initially wanted to become a priest. Instead, he let his Christian beliefs guide his social policies.

However, later in life, his writings on Christian theology showed increasing skepticism, despite being a life-long believer.

In his last book, released in 2017, he wrote that churches must come out and honestly admit: "We do not know whether there is a life after death, but we hope for it, and whoever cannot believe should not be labelled a sinner."

dm, se/kms (dpa, KNA, AFP)