Party spokesperson Abhishek Singhvi also said on Twitter that BJP chief Amit Shah may have to apply for a new job in the party in the wake of the electoral reverses.
In a series of tweets, he said "Surprised Mr Modi Within 100 days itself the people of India are voting for a Modi free india!"
"UP said no to Amit shah and yogi's brand of politics. Namo must introspect."
Singhvi insisted the law of diminishing returns applies in an accelerated manner to BJPs "communal divisive politics and this is exactly what happened today".
"Those like Modi and BJP who sleep the smug, complacent sleep of communalism deserve the rude awakening given by the electorate today. Amit Shah may have to apply for a new job in BJP".
With "Love Jihad" issue boomranging on BJP, Singhvi wondered "either BJP doesn't give importance to local issues or Love Jihad is a foreign issue"
"Campaign creativity evident by the fact that despite many existing issues in UP, precedence was given to fictional ones like Love Jihad", he said in a jibe at the ruling party.
Party leader Rashid Alvi said the reverses for BJP was a "victory" of secularism in the country as people from Gujarat to Uttar Pradesh have voted against communalism.
Congress Media Department chairman and party General Secretary Ajay Maken tweeted that the bypoll results blow showed that the Modi government has had the "shortest honeymoon".
This, he said, was because the tally of the ruling party has come down from 42 to 21 seats in various states when bypolls for 54 have been held so far.
"#BJPByPollBlow Shortest Honeymoon for any Government #BJPExposed A fall from 42 to 21 seats of 54 in just 120 days", he said on Twitter.
Party general secretary Digvijay Singh also took a dig at BJP over the bypoll results saying "good days are over for it".
"Achhe Din for BJP over Losing sitting seats for BJP should be a matter of concern. Congrats for all the Congress Winners. Keep it up," he tweeted.
Good Days are to come was a key slogan of the BJP during the Lok Sabha polls.