Last month the chemist was criticised for refusing to cut the cost of the branded tablet Levonelle over concerns it could lead to "overuse".
The cheapest pill will now cost £15.99.
The British Pregnancy Advisory Service was accused by the pharmacy of bullying its senior bosses by asking women to write to them.
It's asked BPAS to remove personal email details from their campaign widget and to agree not to encourage personal abuse of their people.
BPAS launched its campaign for affordable emergency contraception in November 2016, and nearly all the largest pharmacies have now lowered the cost.
Executive Officer of Right to Life Peter Williams told Premier Boots is right to complain about BPAS's campaign, but the situation highlights the power of public advocacy.
He said: "If more Christians... were more active in making sure they did write to people like Boots, but also any other group that is attempting to expand the use of this sort of drugs, they would have an effect as well."
Williams urged Christians to think "very seriously" about companies that it supports in light of this controversy.
He said: "We need to think very seriously about whether or not it's ethical for us to patronise those organisations that do things that in a very direct way violate our moral standards.
"What we should be saying is we're going to choose to patronise those shops that have a better ethical viewpoint."
He told Premier he will encourage members of Right to Life to write to Boots and inform the company that they are less likely buy from Boots because of its decision.
Boots described emails and comments on social media as a "torrent of personal abuse" against their employees because of its original stance of refusing to lower the price of the morning-after pill.
But BPAS said Boots failed to provide any evidence of abuse sent through the campaign and "comprehensively misrepresented" messages from members of the public.
Peter Williams said Boots acted "cowardly" for changing its mind.
He told Premier: "They should have said 'no, we defend this idea and we think it's absolutely right'.
"But I don't think they had quite as much of an ethical viewpoint, so consequently simply caved to it. I think that's disgraceful on the ethical implications of this. "
Listen to Peter Williams speaking with Premier's Eno Adeogun here: