Which code are you proposing? What will be in it? Those questions have to be answered before answering whether it would be good for the entire world.
I do think that a one world government would be great in some respects, having a common currency, ending wars, free movement of people, cooperation, economic flourishing. But how it is run is highly relevant, and individual nations need to keep some degree of autonomy and independent decision-making.
Some balance between representing the world population as a whole and individual nations would need to be struck. There should be a legislative body similar to the Senate in the US. The population-based body on the other hand I think should be based on proportional representation. People should vote for a political party and parties should receive a proportion based on the percentage of votes they get. People should also rank candidates nominated by their party and then which candidates in a given party list get to fill the seats could be chosen according to instant run-off voting. This way people would be represented proportionally but would still get a say in who the individual representatives are.
As to the executive branch we should have a president. People should get to elect their leader, not have the legislature elect him or her. But instead of the way it's done in the US we should have the president elected by popular vote with an instant run-off voting system.
To prevent gridlock and prevent excessive pork barrel spending there should be limits on filibustering and also the ability of both the executive and legislative branches to vote on or to pass/veto individual line items.
Better yet when the legislative houses meet they should just straight vote on the bill, and there should be a period leading up to the bill where politicians, organizations, and just any member of the public can arrange for a debate and the media can report on it. When they actually meet in session to vote then they should just vote.
In india hindu is majority and muslim, christians are minority. How come uniform civil code be good for a society with un equal population distribution. It is like one adult and two minors. One law for all of them. Will that bring justice? I don't think so. Therefore i disagree.