The trinity does not mean that God is both one and three in the same sense or relationship. It means that God is one and only one in His essense (God, Being) but three in His persons (Father, Son, Holy Spirit). Person and essence are not the same. Person reveals who He is (Father, Son, Holy Spirit), and essence refers to what He is (God, Creator). When Jesus prayed to the Father, It was the person (Jesus) praying to the Father but not the Father praying to the Father. When Jesus died, it was his father and the Holy Spirit that resurrected him although it was really his body that died not his spirit. When Jesus (God) calls the Father my God, it is the person calling the other person but both are the same Being. This is how we can understand the scriptures.