This is probably a cast steel alloy bell (it should hold a magnet). It was probably cast about the time your church was built. Steel alloy bells were cheap compaired to a bronze bell of similar size and had an excellent tone. A No. 20 is more commonly a school bell or would have been used by a small church. These are similar to CS Bell steel alloy bells and were manufactured in large numbers. There is information concerning the American Bell Foundry elsewhere in this forum. Enter American Bell Foundry in the Search box in the upper right hand corner and you should be referred to other sites in this forum.
Harry Long, MD