Matthew 24:36 Vs... The May 21st Rapture people....?

36"But of that day and hour knoweth no man, no, not the angels of heaven, but my Father only."-----SO MY QUESTION IS... Are these folks calling Christ a lier??... Because CLEARLY.. He said NO one knows but God.. How do these "Christians" ignore this??.... I really hate it when people give TRUE followers of Christ a bad name...ruins all our efforts.. But tell me what you think..