I agreed with you that 25th December is not the birth date of Jesus. 25th December is the shortest day in the Northern hemisphere, known as the “winter Solstice”. It was also the day when Constantine worshipped his god - sun god. When Constantine became the sole emperor of the Roman Empire, it was him who decided to celebrate the birthday of Jesus which was already celebrated as the birthday of the sun. The question here is - should christians celebrate Christmas, immersed in the celebration ? Bible teaches the Principle of Holiness (Separation). 2 Corinthians 6:14-18 explain clearly the answers.