Great Sermon! What the Westminster confession means by deduction from scripture is that comparing scripture with scripture truths are deduced that may not be expressly stated. Jesus himself used this method in Matt. 22:31,32 where he proves to the Sadducees the resurrection from the passage on the burning bush where there is nothing "expressly" stated about the resurrection but a resurrection can be "deduced" from the information in the passage. As for the contention concerning credalism a church must necessarily sum up what it believes the Scripture teaches . Your church does this too, that is why it says it is a "primitive baptist" church. This claim in itself is a kind of creed.