What does Liberate 2014/Tullian mean by 'One Way Love'?

My question is prompted by the [Liberate 2014 Conference and the concept of One Way Love](http://paultripp.com/what-i-like/posts/liberate-2014-one-way-love) . There's also a book by a pastor Tullian Tchividjian called "One Way Love". What does Liberate 2014/Tullian mean by 'One Way Love' and what is their understanding of man's role in reciprocating per 1 John 4:19? > We love because he first loved us. *(1 John 4:19)*