An extremely rare 19th century US gold coin featuring one of the earliest uses of the motto 'In God We Trust' will help an Indiana congregation secure its own church building.

According to the website Art Daily, the coin survived an attempted theft at the donor's home four years ago, and was recently given to the GracePoint Church in Valparaiso where Pastor Ben Lamb described it as 'an incredible gift in God's story'.

'This is one of only 10 known surviving 1866 proof Liberty Head double eagles with the In God We Trust motto,' said Sarah Miller, Director of Numismatics at Dallas, Texas-based Heritage Auctions' New York office. It is expected to sell for $300,000 or more in a public auction in the Chicago suburb of Schaumburg, Illinois and online on April 27, 2017.

'According to United States Mint records, only 30 proof Liberty double eagles were struck in 1866,' Miller explained. 'Today we can track only 10 known surviving specimens, and three of them are part of permanent collections, including one in The Smithsonian Institution. The In God We Trust motto first appeared on US coins in 1864, starting with copper two-cent denomination coins, and was used on $20 denomination gold coins starting in 1866.'

A widow who wishes to remain anonymous gave the coin to the GracePoint Church earlier this year as 'seed money' for the congregation to build its own church building.

The congregation was founded in 2009 and has been conducting Sunday morning services in an elementary school up to now. Lamb consigned the coin to Heritage to launch the church-building project.

He said: 'The donor's husband was a quadriplegic for many years and used his time to study investing, including coin collecting. This was the very first one he ever purchased. He passed away 14 years ago, and she held onto the coin. Four years ago she was attacked at home by four assailants who wanted to steal the coin, but she and the coin were saved by a neighbour. She told me that after the attempted theft it had been a thorn in her side.

'The widow told us the coin was rare, but we never dreamed how huge the true value was or the money it could ultimately bring for GracePoint Church. We were down to just a couple days to meet our financial deadline for our new building, and Heritage immediately wired GracePoint $150,000 (advance payment toward the final price realised at the auction). We were absolutely blown away! Honestly, we were completely stunned by the value of the coin.'

The coin was authenticated as genuine in 1992, Art Daily reported, and graded Proof 65 on a scale of 1 to 70 by Numismatic Guaranty Corporation, one of the world's largest rare coin authentication companies.

'This coin is an incredible gift in God's story. Although this gold piece brought grief to the widow for many years, ultimately it brought incredible joy,' said Lamb. 'It's ironic that the last few hours before our financial deadline, the congregation had to do exactly what the coin's motto said over a hundred years ago: trust God.'