Religion is derived from religio in Greek which means believe in something firmly. There is a fundamental difference between Confucianism and religions. In religions, usually we have to believe in something that is impossible for us to confirm its existence unless we believe it firmly. God and Buddha falls on this objective, but in Confucianism there's no such objectives. All his teachings are understandable in line with our ordinary daily life. Confucianism is ethics at best, it's far from religion.

Religion is not merely the sum total over a persons view of the universe, his sense of the goal in life, and his means of moving toward that goal. But it requires objective of admiration.

Some people use the word religion very roughly like thought, morals, ethics, so I am not in the least opposing to the use of the word in many senses