District secretary Kainulainen evolved in the mid-1960s as one of the Communist Party's opposition main players. He strongly condemned any form of revisionism, which represented the majority party led by
Aarne Saarinen. Kainulainen was a rhetorical man and easily conflict-prone. In the spring of 1968 he was sought to be dismissed from the SKP Political Committee. However, he survived with a warning. In the fall of 1968 Kainulainen supported the
Occupation of Czechoslovakia, which on the other hand SKP condemned.[4] The Opposition
Tiedonantaja magazine, originated from the Tiedote (Newsletter) magazine of the Uusimaa District, was founded by Kainulainen in the autumn of 1967. As the first editor-in-chief he recruited his faithful assistant Tauno Wallendahr. Kainulainen was a key figure in the process of turning it into a joint publication of the entire opposition in the autumn of 1968. At the 15th assembly of the SKP in 1969, Kainulainen led the opposition that was condemned by the majority. Opposition representatives marched out of the meeting after Kainulainen gave a sign. At the rebellion meeting in the Koitto House in Helsinki, Kainulainen supported the establishment of a new ideologically
orthodox communist party, but was in a minority with his opinions. Kainulainen negotiated about the new party among others with the
Soviet Union Communist Party, but the idea was not accepted by the Soviets. In April 1969, Kainulainen was elected as the executive committee secretary of the Communist Land Advisory Board, which was founded by the opposition. In the 1970s Kainulainen continued his principled struggle against
revisionism and he was alongside
Taisto Sinisalo and Urho Jokinen one of the most visible figures in the
taistoism movement. He was responsible for the opposition economy through many associations. In the
elections of 1975, Kainulainen was elected to the parliament via the SKDL lists. He was a member of the legal committee. Kainulainen departed from parliament in the next elections, but returned to parliament in 1982 for a six-month term to replace
Ilkka-Christian Björklund, who was appointed as General Secretary by the
Nordic Council. Under the leadership of Kainulainen, the SKP's Uusimaa district was firmly in the hands of the opposition and represented the left wing of the taistoism group. == Disputes with Taistoist-movement ==