Going through the Preamble of the HMA 1955, the division bench of the Supreme Court held that the marriage of a Hindu with a Christian is void ab initio.

From Para 18,

18. Although, an attempt has been made to establish that the Hindu Marriage Act, 1955, did not prohibit a valid Hindu marriage of a Hindu and another professing a different faith, we are unable to agree with such submission in view of the definite scheme of the 1955 Act.

From Para 20,

20.As submitted by Mr. Rao, the Preamble itself indicates that the Act was enacted to codify the law relating to marriage amongst Hindus. Section 2 of the Act which deals with application of the Act, and has been reproduced hereinabove, reinforces the said proposition.

From Para 21, Use of ‘may’ in section 5 of HMA

21.Section 5 of the Act thereafter also makes it clear that a marriage may be solemnized between any two Hindus if the conditions contained in the said Section were fulfilled. The usage of the expression ‘may’ in the opening line of the Section, in our view, does not make the provision of Section 5 optional. On the other hand, it in positive terms, indicates that a marriage can be solemnized between two Hindus if the conditions indicated were fulfilled. In other words, in the event the conditions remain unfulfilled, a marriage between two Hindus could not be solemnized. The expression ‘may’ used in the opening words of Section 5 is not directory,  as has been sought to be argued, but mandatory and non-fulfilment thereof would not permit a marriage under the Act between two Hindus. Section 7 of the 1955 Act is to be read along with Section 5 in that a Hindu marriage, as understood under Section 5, could be solemnized according to the ceremonies indicated therein.

And finally in Para 22,

22.In the facts pleaded by the respondent in her application under Section 12(1)(c) of the 1955 Act and the admission of the appellant that he was and still is a Christian belonging to the Roman Catholic denomination, the marriage solemnized in accordance with Hindu customs was a nullity and its registration under Section 8 of the Act could not and/or did not validate the same. In our view, the High Court rightly allowed the appeal preferred by the respondent herein and the judgment and order of the High Court does not warrant any interference.

Citations : [2009 MPLJ SC 2 48], [2008 SCALE 16 109], [2008 AIOL 1405], [2009 MHLJ SC 2 850], [2008 SCR 17 35], [2009 ALLMR SC 1 488], [2009 BOMCR SC 5 906], [2009 SCC 1 714], [2009 AIR SC 244], [2008 JT 13 450], [2009 SUPREME 1 145], [2009 SCC CIV 1 326], [2009 AIR SC 1085], [2009 AIC SC 74 33], [2009 CHN SC 1 158], [2009 AIR SCW 244]

Other Sources :

https://indiankanoon.org/doc/421764/

https://www.casemine.com/judgement/in/5609ae6ae4b0149711413cbe