Most of secular countries have banned polygamy, India allows Polygamy for Muslims only

World Polygamy abolition status

  Polygamy permitted and practiced

  Legal status unknown or ambiguous

  Polygamy generally illegal, but practice not fully criminalised

  Secular countries where Polygamy fully outlawed/abolished and practice fully criminalized

India - Polygamy allowed for Muslims only

A majority of the world's secular countries (more than 98%) and nearly all of the world's developed nations do not permit polygamy, and there have been calls for the abolition of polygyny in many developing countries, India violating secular principals, permits polygamy for Muslims alone. Even Indonesia being largest Muslim country has banned polygamy for Muslim civil servants.

Polygamy remains legal for Muslims under the terms of The Muslim Personal Law (Shariat) Application Act of 1937, as interpreted by the All India Muslim Personal Law Board" According to the 1961 census (the last census to record such data), polygamy was actually less prevalent among Indian Muslims (5.7%) than among several other religious groups

Though Hinduism accepts both monogamy (single wife at a time with reference to Lord Rama) and polygamy (with reference to Lord Krishna who had 8 wifes), Indian Judiciary does not allow polygamy for Hindus and permits polygamy for Muslims which contradicts secularism

A sample list of countries having polygamy banned:

Country	Date	Prohibition type
United States	July 1862	Morrill Anti-Bigamy Act, which made polygamy a misdemeanor offense in US territories and other areas where the federal government has exclusive jurisdiction.
United States	March 1882	Edmunds Act, which reinforced Morrill by making polygamy a felony in the jurisdictions covered by Morrill; also prohibited "bigamous" or "unlawful cohabitation" as a misdemeanor offense, which removed the need to prove that actual marriages had occurred in order to obtain convictions on polygamy related charges.
Turkestan ASSR(modern Kyrgyzstan)	October 1921	Outlaws polygamy[49]
Thailand	October 1935	Outlaws polygamy; polygamous marriage[50]
North Vietnam(modern Vietnam)	October 1950	Outlaws polygamy
Syria	1953	Restrictions on polygamous marriage[39]
India	1955	India allows polygamy for Muslims only. Outlaws polygamy; polygamous marriages (No pollygamy for Hindus)[51].
Tunisia	1956	Ban on polygamy; polygamous marriages[52]
Iraq	1959	Ban on polygamy; polygamous marriage[39]
Côte d'Ivoire	1964	New penal code outlaws polygamy; polygamous marriages (upholds existing)
British Hong Kong (modern Hong Kong)	1971	Outlaws polygamy[53]
Eritrean People's Liberation Front(modern Eritrea)	1977	Outlaws polygamy; polygamous marriage (districts under Sharia exempt)[54]
Egypt	1979	Restrictions on polygamous marriage; ease of divorce laws[52]
Egypt	1985	Restrictions on polygamous marriage (less liberal)[52]
France	1993	Outlaws family reunion for polygamist immigrants[55]
Uganda	December 2003	Outlaws polygamy[56]
Morocco	2003	Restrictions on polygamous marriage[52]
Benin	August 2004	New penal code outlaws polygamy; polygamous marriages (upholds existing)[57]
Morocco	February 2005	Restrictions on polygamous marriage (heavy restrictions)[58]
Uganda	July 2005	Outlaws polygamy[59]
Indonesia	2007	Bans civil servants from living polygamously[60]
Morocco	May 2008	Restrictions on polygamous marriage (heavy restrictions)[citation needed]
Uganda	June 2008	Outlaws polygamy[56]
Iraqi Kurdistan	Nov. 2008	Abolishes polygamy except in selective circumstances[61]
Mayotte	March 2009	Mahoran status referendum, 2009 (passage abolishes polygamy)[62]
Turkey	May 2009	Disallows polygamists from immigrating into the country[63]
Indonesia	July 2009	Restrictions on polygamous marriage[64]
Namibia	July 2009	Ban on polygamy & polygamous customary marriages

Reference:

http://www.newdelhi.msz.gov.pl/resource/e75c9c6a-42be-465e-822d-29bc1d01cc1d:JCR

https://en.wikipedia.org/wiki/Legal_status_of_polygamy

http://indiankanoon.org/doc/1325952/