Cornerstone 1420 x 500
Crossroads 1413 x 455
Grace Chapel 1465 x 625
LifePoint 915 x 455
New Hope 1580 x 610
Northshore 800 x 460
Reunion 913 x 455
Synergy 1390 x 570
The Well 1435 x 590
True Life 1415 x 460
Westend 913 x 455
You will want to ensure that your images are near to these sizes for each template because at this time there is not a way to crop/resize images once they have been uploaded to the site.