According to the Guarding UK:

In a policy paper from the Holy See, Pope Benedict pins the blame for the international financial crisis largely on ‘offshore centres’, many of which, such as the Channel Islands, are British dependencies.

‘They have given support to imprudent economic and financial practices and have also played a significant role in the imbalances of development, allowing a gigantic flight of capital linked to tax evasion,’ says the report. ‘Offshore markets could also be linked to the recycling of profits from illegal activities.’

The Pope points to estimates that the global fiscal deficit caused by offshore activities could amount to a staggering $255bn (£175bn) which is ‘more than three times the entire sum of [global] development aid’.

It sounds like Romney is doing the best he can to hide from being transparent, yet, he cannot earn the public trust without first being transparent.  President Obama has already released his tax returns, and Americans believe that Romney has a lot to hide.

Me thinks it has everything to do with offshore centres and tax havens the Roman Catholic Church has identified.