Day of reckoning looms over deal with the biggest-mouthed bigot.
The longer the bank remain linked to the Bible-bashing ranter, the more embarrassing he becomes - and the closer a boycott by customers becomes.
Until now, Robertson has only (!) offended gays, feminists, Moslems and Hindus. This time, he has consigned the whole of Scotland to hellfire.
For daring to challenge the bank's links with the biggest-mouthed bigot in broadcasting, Scots are unChristian and uncivilised.
If the Bank of Scotland stand by the name they have traded under for 300 years, they must break their links with this arch-zealot.
If the bank swallow his insults to Scotland, the steady trickle of customers closing their accounts deserves to become a Biblical flood.
They will not deserve the name Bank of Scotland - because the majority of Scots are not narrow-minded and intolerant.
Bankers are used to having a reckoning and theirs will come in two weeks when the bank's AGM should become a stormy protest rally.
No doubt, the new governor Sir John Shaw, chief executive Peter Burt and the rest of the board believed that once they got past that hurdle, the issue of the Robertson deal would just go away.
The money from the telebanking joint venture with Robertson Financial Services would come rolling in.
A target pounds 2billion in three years would far outweigh the losses caused by a minority of politically-correct ethical investors.
It just might have - if Robertson had not preached his bitter anti-Scottish sermon.
Now, they will either have to rethink and retract the Robertson deal - or take the consequences.
Robertson claims not to recognise himself in the descriptions of "a Bible-thumping extremist".
But he admits: "I will bring my faith to any venture in which I become involved."
At least he is honest - and the Bank of Scotland directors should have known what they were letting themselves in for.
They should have known not to get into bed with a right-wing rabble-rouser. Once they did, only a supercilious arrogance has kept them there.
The righteous anger of offended Scots should convince them their Robertson relationship is a business marriage made in Hell.