Complex sentence: They started from Ayodhya with a mission and vision to spread Hinduism to counter growing influence of other religions, particularly, Islam and Christianity and also to preserve and propagate the practices of Vedas and Hindu culture which was under threat from other religions in a broader context.
Split into simpler sentences: They started from Ayodhya with a mission to spread Hinduism in order to counter growing influence of other religions, particularly Islam and Christianity. They also sought to preserve and propagate the practices of Vedas and Hindu culture which was under threat from other religions in a broader context.