I am a Christian, middle class and he is Hindu. We are in love since 3 years. I've not yet spoken about this to my parents. My parents are very strict that they'll not marry me a hindu guy. I know he is the right guy for me but I don't know how to prove this to my dad. Please suggest me some ideas to convince my parents.

You have deceived your parents for 3 years knowing how they feel about you marrying a Hindu. I would suggest if there is no physical danger to you is start talking honestly to your parents and give them time, a year or two to actually deal with not only there belief but YOU breaking their rules.

That will also give you and this fellow ime to make a decision about what you both will do if they never approve of your marriage which is a distinct possibility. There is no magic argument that is guaranteed to change their minds. Sorry,but start with being honest, and planning for them NOT to approve and figure out what YOU will do about it.

For now you can only get the support of family and friends, or a trusted respected religious leader and probably should start with your mom.

How old are the both of you? Are either of you independent without financial support of your families? That's the most important factor whole discussion.

I am 70 yrs old, divorced after 7 yrs in 1975, then remarried for 30 yrs, now a widower. I do feel for you, since this is a different religion question. The old saying that "when you marry, you also marry the relatives", is very, very true. You marry each other's family, and it will be a problem, unless you move 3000 miles away from them.
Please, give this some more time, and be honest about it with your parents and his. You both need time to think hard about this. I do wish you the best.

We both r 23 and both r working.. my parents do accept love marriage but.. only if he is of my religion... the only problem is our religion

The question of religion is your parents problem not really yours. The way you and your love deal with your parents is the problem. Do you really need permission, or a blessing from them?

What are you willing to do if you get no permision, or blessing from them? How will your children be raised?