Vasilijs Apilats, 61, of Edleston Road, Crewe, stole The Raising of Lazarus painting from Chester Cathedral in 2014 and left a cheap Christmas toy angel in its place, the court heard.
Apilats denied theft and told Chester Crown Court he bought the icon for £135 from two men he believed were cathedral officials.
But he was found guilty and will be sentenced in January.
The painting is estimated to be worth £2,000 and was probably made between 1870 and 1880, the jury was told.
It was taken from the altar of the cathedral's Chapel of Saint Anselm and recovered from Mr Apilats' home a month later.
Mr Apilats, who is originally from Latvia and spoke to the court through an interpreter, claimed a man who approached him in the cathedral sold him the icon and a second man "approved the sale".
He denied placing the toy in the chapel.
Caroline Harris, prosecuting, earlier called his explanation "elaborate, fanciful and far-fetched"
A man has been found guilty of stealing a cathedral's 19th Century Greek icon.