He said Ms Gandhi would widely quote from the ancient scriptures in public speeches.
Pandit Nehru would also do so but he was careful about his "public display of religiosity", Mr Ramesh said.
The former Union minister was speaking on 'Remembering Indira Commemorating Her Centenary" at the Tata Litfest 2017 here.
"You asked me the question - why is the BJP more Indira Gandhi-friendly than Nehru-friendly? There are two reasons behind it.
"One is she did what she did in 1971, she dismantled Pakistan (leading to creation of Bangladesh) and secondly... she was publicly willing to demonstrate the fact that she was steeped into the Upanishads, the Rig Vedas. In every speech of hers, she quoted from the Atharva Veda, or from the Aranyaka Upanishad," he said.
Mr Ramesh said the country's first Prime Minister Jawaharlal Nehru would also quote religious texts in speeches, but would be careful about his public display of religiosity.
"She (Indira) was in Stockholm in 1972 (for a UN conference on environment) when she finished her most famous speech with a long quotation from the Atharva Veda. She was always quoting some Sanskrit shlokas," he said.
Former Union Finance Minister P Chidambaram and other diplomats were also part of the discussion.