What is the basic difference between Islamic marriage, civil marriage and Christian marriage?

The diference between Islamic marriage, Civil marriage and Christian Marriage is: 

1). Islamic marriage is polygamous or Potentially Polygamous. 

2). Civil Marriage is presumed to be monogamous. However, a monogamous marriage contracted to civil form may be converted to polygamous marriage if the parties thereto make a declaration on their own free will. See section 11(1) of Law of Marriage Act. 

Note: Declaration under subsection (1) should be made before the judge, RM or District Magistrate as per section 11(2) of the Law of Marriage Act. 3). Christian Marriage is Monogamous and cannot be converted from monogamous to polygamous if both parties thereto continue to profess the Christian faith. See section 11(5) of Law of Marriage Act.

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