"Testament" means COVENANT ("agreement", "compact",etc.). The old way of worshipping God was done in the way of RELIGION, the NEW way of worshipping God is done in the way of "Love" (compassion) according to the Holy Spirit and involves genuinely caring about the welfare of your fellow human being. The Old Testament is good for background and understanding, but the New testament specifies how we should worship because the Lord is the mediator of a NEW covenant (Hebrews 9:15).