Theory

Affirmative Opinions (Indicative Mood): Use expressions like Creo que, Está claro que, Es verdad que or Es evidente que followed by the Indicative mood because you are stating a fact or a firm belief.

Negative Opinions (Subjunctive Mood): Use expressions like No creo que, No está claro que, No es verdad que or No es evidente que followed by the Subjunctive mood to express doubt, denial, or uncertainty.