What was the main source of contention leading up to the french and indian war?

The territory. The increase of the population in the British colonies made an expansion necessary,  the French territories made that impossible, even when they had little population but a lot of uninhabited territories. India had a bad vision of both.

The religion too, the English were Protestants and the French were Catholics.

basic principles: federalism, separation of powers, checks and balances, judicial review, representative democracy, limited government, rule of law, individual rights and responsibilities, consent of the governed, majority rule, popular sovereignty, equal protection.