How can you tell when someone is lying to you?

I have a list of 10 conversation starters from http://www.gettoknowu.com/


How can you tell when someone is lying to you? I would like to say it is a gut reaction but I am terrible at telling when I am being lied to. It is usually a cognitive process where I notice what the person is saying is contradicting something else they have said.
Not counting your religion, which religions do you find interesting? Why? The thing I find interesting is these prosaliting atheist. There is a who group of atheists that are militant about converting anyone to their why of thinking. They are more aggressive than even the most hardened evangelical.
What makes you jealous? As I get older I need to jealously guard my time.
Do you feel you have a purpose or calling in life? I am still trying to find it.
Who taught you to cook? My mother and television.
Who do you admire as a leader? Churchill
What story from history inspires you? The Mormon Pioneers
Do you believe in God? Very much so.
When was the last you where caught in a lie? “let me call you back”
If you could repeal one law what would it be? Tax Laws, need I say more.