If you were to read the end of almost every book in the "New Testament", and Jesus's last words, you will notice that God will keep his return secret.
Since the book of Revelation was written in 700ish AD, there is still speculation about its weight in comparision to the Old and New Testament. It contridicts what Jesus and the Disciples have said about God's second coming. Jesus himself has said, not the exact words, but, "The Angels do not know, mankind does not know, and I do not know when I will be back." - Jesus.
If Jesus doesn't know when God will return, how can someone know 700 years after his son's crusifixtion (sp?). That makes no sense at all.
The exact date and time of Christ's return will be secret, but it's kind of hard to miss 'and the Lord shall descend with a shout'. This is not a contradiction. Just because the time of the return is secret does not mean the actual return will be secret. John does not specify a time anywhere in Revelation--he only specifies the events surrounding end-times. It's like when you have friends coming to visit you--you might not be 100% sure of their arrival time, but you'll know when they arrive when you see their car and hear them come to the door.
Revelation was written about 69 AD by John, not 700 AD. A number of early church leaders as early as the 100's AD mentioned Revelation and it's mentioned in the canon list in the Muratorian Fragment (
http://www.bible-researcher.com/muratorian.html[/url) from around 170 AD, so it's impossible that this was written in 700 AD.