The Buddha never claimed that he was a son of god or a messenger of god.
The Buddha is not an incarnation of any god who appears in this world. Nor is he an incarnation of a previous Buddha. Many Buddhists seem to have the mistaken view that the same Buddha appears in this world from time to time. Actually, different persons become Buddhas in this world. Anyone can become one of these Buddhas; but first he must develop and possess the necessary qualifications and attributes. These qualifications and attributes take many, many life-cycles to perfect.
Some orthodox people in India absorbed the Buddha and his teachings into their faith by claiming that the Buddha was an incarnation of their god. Although Buddhists believe that the Buddha was in one of the heavens in his previous birth, they do not claim that he came down to this world as a representative of any god.
Even today, certain religionists are trying to absorb the Buddha into their fold by claiming that the Buddha himself had predicated that another Buddha would appear in this world 500 years after his death and this latest Buddha will become even more popular. They named another religious teacher who lived 600 years after Gotama the Buddha as the latest Buddha. Thus they advise the people to give up their old Buddha and to follow this new Buddha. However, we must be grateful to them for giving the same status to the Buddha as to their religious teacher. But we feel that this is probably another attempt to absorb Buddhism into another faith. Those who try to introduce this so-called new Buddha as the enlightened one must realise whether this new Buddha also has the same characteristics as Gotama the Buddha. Certainly there are different views regarding the teachings of these two religious teachers. There is no doubt that the Buddha had mentioned that there will be another Buddha who will appear in this world, but it is very clearly recorded that this future Buddha will appear only in India at some incalculable period (in terms of years) in the future.
Taken from "What Buddhists Believe"
Written by Ven. K. Sri Dhammananda
Published by Buddhist Missionary Society