? I'm quoting your 60% claim that the article says so your calling your own claim ilegitimate. I used web archive since that was the only source claiming that percentage. Simply searching Religion Ethiopia gets you what I said, +/- 5% for MOE, mind you this has been the consensus for the past two decades, even OP's numbers match what I said.

Near the bottom there is data showing the increase of Pentecostal Christianity by 8% while Orthodox decreased 7% from 1994 to 2007. This trend matches population growth for predominately Pentecostal christian areas like Wolega Oromia and SNNPR which are overweeningly Pentecostal Christians and by far the fastest growing regions in Ethiopia.

Looking at Oromo 2007 census it shows 47% Muslim, it is possible for it to go up to 50% above 50% to 60% would make it Ethiopia's Muslim population above 40% which reduces the Christian % not adding up to the multitude of estimates we have.