Love marriage problem

Respected sir/madam, I'm a 17yr old christian girl and i'm going to complete my 18th year in 4 months from now. i am in mutual love with a boy aged 23 years who is currently working as a civil engineer in IL & FS metro constructions with all my conscience. this is my own decision without any one's pressure. we want to marry each other not immediately but after 2 years, My to-be in laws have accepted our proposal but my parents are not at all ready for this.. it would be okay if they rejected because of my age.. but this is not the case.. my minority is going to be finished.. but the cause of their opposition is that.. he belongs to some other group of christianity i.e, roman catholics while we are jehovah's witnesses. basing on this only reason they are rejecting our love. i'm facing so much of harrassment and violence in my house.. they even house arrested me since the past 3months.they are warning us that they will book false cases on him and his parents and destroy his career. they are warning me to stay away from him or else they will kill him and perform my marriage with some one else without my consent forcefully. Are there any rights that i have so that i can fight for my love? and get married without any problem? can i seek security from police? i need legal advice as to how to be safe against PHYSICAL HARM to self and my love and his parents and also my boyfriend to be eligible to do my job properly without losing his Job or my love.. PLEASE GUIDE ME WITH THE PROPER LEGAL PROCEDURE I HAVE TO FOLLOW FOR MARRIAGE, IMMUNITY AGAINST FALSE CASES AND PROTECTION IF POSSIBLE TO MY PARENTS.