Marriage certificate which is given by the church pastor is valid or not ?

Sir, Im Joshua.m aged(20) . I need a proper information about marriage & will it valid in Indian law. In 2020 ,August on 29th i got married to a hindu girl in church and im a christian. Her age is 21 . she was born in September/21/1999. Reason for marriage: SHE WAS IN CARRYING(PREGNANT) After knowing that she is pregnant i thought to take her away but due to my family i was not supposed because i grewup in a decent family so i thought to take this up to her parents and i went to her home and said what exactly happened and i assured that we will get marriage with your concern and somehow we got married in 20days. I married her in a church and the pastor who solemnized my marriage gave me a marriage Certificate after completion of marriage and now i wanted to change her Surname to my name and in this year on May/20/2021 I complete my 20 and ill get 21 years so i can use that certificate to change her details and her C/o details into my will it useful or do i need to apply marriage certificate under special marriage certificate and i can see that boy must complete21years so what happens if i apply in register office and please help me in this. Thankyou.