The Symbol you see that represents the O for God, is the trinity symbol. The trinity represents the belief that God is one Being made up of three distinct Persons who exist in co-equal, co-eternal communion as the Father, Son and Holy Spirit.
According to New Testament (Matthew-Revelation), the Father is God (John 6:27; Eph. 4:6), Jesus Christ is God (Heb. 1:8), and the Spirit is God (Acts 5:3-4).
The 3 rings represent the Father, Son and the Holy Spirit, and the second symbol you see inside the 3 rings is a second version that represents "Trinity" as well.The 7 holes inside of it represents "Perfection" And on the seventh day God ended his work which he had made; and he rested on the seventh day from all his work which he had made.
According to Old Testament (Genesis 2:2),And on the seventh day God ended his work which he had made; and he rested on the seventh day from all his work which he had made.