Look at these expressions of positive and negative (using negations) opinions (i.e. using affirmative or negative sentences):
Note that with the following expressions of opinion, the mode of the following verb changes whether the opinion is expressed in an affirmative or negative form (using negative structures like ne...pas etc).
penser que + Indicatif (to think that) / ne pas penser que + Subjonctif
trouver que (to find that)
savoir que (to know that)
croire que (to believe that)
prétendre que (to claim that)