The ancient Greeks and Romans believed that some dreams were sent by the gods and held prophetic properties. There are hundreds of inscriptions that show figures in Ancient Roman society made dedications and donations based on prophetic dreams they had experienced. This vein of thinking has survived in the monotheist and polytheist religions today, with many holy books describing a divine intervention in the mortal world through the vehicle of dreams.
In the Old Testament of the Bible alone, there are more than 120 mentions of dreams. They are used both to give instruction directly from God and prophesize about the future. In the New Testament, Jesus gives a vision of his future kingdom to Peter, James and John in the form of a dream. In Genesis, dreams are used to warn global leaders of future events. The Torah and Qu'ran also both feature dreams as a method of communication from God. They offer divine comfort, warning of impending danger and glimpses of the future. When circumstances warrant, Gods present prophesies and messages to their servents through dreams. This is not to say that every dream is a dream directly from a divine being. The Gods, in most religious lines of thinking, reserve their dream interventions for moments when they are most required. This view of dreaming has fallen out of mainstream Western thinking, where the realm of spirits and supernatural forces that play a role in our dreaming is often overlooked but it is still highly prominent in other cultures. In African cultures, Christians and non-Christians alike place an emphasis on dreams as a direct line of communication with departed spirits. The native cultures of Latin America are also littered with references to incidents which were predicted in dreams.
Even if we assume that Gods can communicate with the individual through dreams, we rely on humans (often religious figures) to tell us which dreams were from God and what they mean. This leaves the dream vulnerable to the individual's interpretation. If some dreams are sent from God but some are not, how can the individual know which dreams are the word of God and which are not? The religious figure has little more than personal speculation to decide which come from God and which do not. This is fallible.
[P1] God/Gods can communicate with us through dreams. [P2] He/she/it/they can reveal introspective insight and future prophesies. [P3] Therefore, dreams from God/Gods can offer accurate information on the present, past and future.
[Rejecting P3] We rely on religious figures to interpret these dreams, leaving them vulnerable to speculation and the fallibility of human judgement.