There have been too many false prophets who have come along claiming to have new scriptures or claiming to be the messiah.... here are a few. We cannot be expected to believe in these people especially when Jesus told us what to expect next and what to look for.
Mirza Husayn 'Ali, (1817–1864), born Shiite, adopting babism later in life, he claimed to be the promised one of all religions, and founded the bahai faith.
Jacobina Maurer (1841 or 1842-1874) was a German-Brazilian woman who lived and died in the state of Rio Grande do Sul who emerged as a messianic prophetess, a representation of God, and later declared the very reincarnation of Jesus Christ on earth by her German-speaking community called Die Muckers (or the false saints) by her enemies, Die Spotters (or the mockers). After a number of deadly confrontations with outsiders, Jacobina was shot to death together with many of her followers by the Brazilian Imperial Army.
Williams Davies (1833–1906) LDS morman schismatic leader; claimed that his infant son Arthur (born 1868) was the reincarnated Jesus Christ.