They are blending Christianity with Marxism for a non-biblical 3rd way.

With the disturbing movement of Progressive Christianity comes the merging of Communism/Socialism(Social Justice) with Christianity. The result is NOT Christianity.

The "Sojourners" is one example of this and Jim Wallace is behind this. According to "Marxianity", he's been behind just about every communist revolution in Central/South America.

This is an excellent 13 min intro to what is going on with this movement.

For a more in-depth presentation

This is an excellent book

Be careful with the Gospel Coalition. You can see the explanation here.