text: why christians has old testiments and new testiments? why not just follow the old testiments?y need to change?   from what i understand, the teachings of jesus and his sacrifice supercede and override the old laws of the old testament.  the old testament was supposed to be a follow up to the true gospel which arrived when jesus walked the world and died to save humanity from its sins.  from that point on, following the old law was no longer necessary for salvation - only the accepting of jesus christ as the true lord and saviour would lead to redemption.