Why are christians worshipping a slave god ?

The religion of the slaves was both visible and invisible, formally organized and spontaneously adapted. Regular Sunday worship in the local church was paralleled by illicit, or at least informal, prayer meetings on weeknights in the slave cabins. Preachers licensed by the church and hired by the master were supplemented by slave preachers licensed only by the spirit. Texts from the Bible, which most slaves could not read, were explicated by verses from the spirituals. Slaves forbidden by masters to attend church or, in some cases, even to pray, risked floggings to attend secret gatherings to worship God.

this is true

the answer is a glaciers carved a large valley that later flooded and became puget sound