Sanders is pushing economics issues. There's absolutely nothing connecting Evangelicals to fiscal reactionary politics the Republicans have been pushing.
Evangelicals have gotten the shaft from the GOP. Generally low in SES, they have paid the economic price for supporting reactionaries. Even with global warming, they are more southern -- and they are more likely to experience harm because the American South has brutally-hot summers as it is. They are also more likely to become cannon fodder in war than other white people. Meanwhile, evangelicals have been losing on the 'cultural issues'.
Poaching the voters who have gotten the least but given the most is good politics, If Barack Obama could pick up Hispanic voters who had most believed in the "Opportunity Society" of George W. Bush and gotten burned most by the financial collapse... maybe Bernie Sanders can appeal to a populism that could emerge anew from its recent nadir.
I do not have a problem with evangelicals making more money because of fairer pay so that they can put more money into the collection plates at church.
