The story of creating new Dharma, which is against Vedic Dharma, to destroy virtuousness of asuras, was mentioned in Chapter 4 to 10 of Rudrasamhita - Yuddhakanda section of Shiva Purana ( Pg:820-846).
For causing obstacles in their virtuous activities, Vishnu of great
brilliance, created a PURUSHA born of himself. He had a shaven
head, wore dirty clothes, held a woven wicker vessel in his hand and a
roll of cotton in his hand when he shook at every step. His hands
tucking at the cloth were weak. His face was pale and weak. In a
faltering voice he was muttering "Dharma,Dharma".
(Footnote says, According to present context Vishnu created a delusive
teacher called Maayamoha who created as Maaya Saastra of 16,00,000
verses in Apabhramsa,preaching Jina Dharma for Misguiding the Asuras.
They preached Non violence, forbade Shruti and Smaarta rituals,
discarded Varnasrama System,created an order for women which resulted
in leaving home and leading the life of nuns. In some versions the
role is assigned to Brihaspati,Preceptor of Gods who in guise of their
preceptor Sukra deludes the Asuras. For details,see
Maayamohanaprakarana in Padma,Vishnu ,Linga and Matsya.)
"O intelligent one , born of me,you are certainly identical with me in
form.Know why you have been created. I shall tell you. You are born of
me. You can perform my task. You are my own. Certainly you will be worthy
of worship. Let your name be Arihat. You will have other auspicious
names too. I shall assign to you a place afterwards. O you who wield
Maayaa,create a deceptive sacred text of 16,00,000 verses contrary to
Srutis and Smritis, wherein Varnas and Aasramas shall be eschewed .Let
the holy text be in Aprabrahmsa Language. Let there be emphasis on
actions. O you with shaven head, you shall go to city of Tripuras,
reveal the Tasmik acts and destroy the three cities. After that,O
great one you shall go the desert stay there carrying your own duties
and activities till advent of Kali Yuga. At my bidding your cult shall
Saying this Vishnu vanished.
Then the ascetic of shaven head acting in accordance with Vishnu's
behest created four disciples of like form as himself and taught them
the deceptive cult.
Those Shaven heads then went to City of Tripuras and taught this deceptive cult. When Asuras stopped worshipping Shiva, Shiva killed them.
After kneeling down before Gods,tonsured heads ask Gods" where shall
Vishnu and other gods said,
"From now onwards in the Kali age those follow this cult will be faced
with disastrous results. We tell you the truth. There is no doubt about
it. O brave tonsured heads, you shall stay incognito in the desert
region. That is my behest. When Kali age begins,you can propagate your
cult. In kali age,deluded fools will follow your cult."
(Footnote says the desert is identified as desert Maru lying to the
north-west of Gujarat or and to the north of Dwaraka which is also called as
Thar or Rajaputana desert.)
That religion could be Jina dharma (Jainism).