Jacob continues using the past tense for the actions of his people at the beginning of this verse, assuming that for the long future readers it will be clear that they were long in the past. He does not seem to be able to sustain that literary convention, however, and returns to a more immediate present tense to describe their worship.
The first sentence of this verse contains a curious repetition: "...worshiped the Father in his name, and also we worship the Father in his name." This duplication obviously follows one after the other, and contains the same functional elements. The sole difference is the tense of the verb.
It appears that this shift is intentional, and that the repetition is purposefully used to emphasize the shift in the verb tense. Thus the also becomes a signal that new information is to be given. Because the new information lies only n the shift in tense, we must suppose that either Jacob is really quite forgetful and simply repeats himself, or that this is an intentional shift in the thrust of the message. All we have seen from Jacob suggests that this is intentional. We can therefore add some emphasis to help us understand the repeated phrase: "Behold, they believed in Christ and worshiped the Father in his name, and also we worship the Father in his name." The shift in tense makes the declaration of their beliefs more current and emphatic.
Jacob next declares that they are keeping the law of Moses as a discipline to point them to Christ. This is a very similar statement to Paul: "Gal. 3:24 Wherefore the law was our schoolmaster to bring us unto Christ, that we might be justified by faith."
It is very interesting that Jacob equates their living the law of Moses to Abraham's test in the sacrifice of Isaac. In that story, we certainly have an example of a faithful man obeying a law, but the undercurrents of the Abrahamic sacrifice give a very interesting light on Jacob's understanding of the law of Moses. Would Jacob had thought the law of Moses as hard a command to live as Abraham did the command to sacrifice his son?
It is most likely that Jacob uses the Abraham story because it points to a story of ultimate salvation, of a purpose to the command that was not precisely what it appeared, but rather transcended the command itself into teaching a larger truth. It is certainly this aspect of the law o Moses to which Jacob refers. It leads to a greater understanding that is much more than the specifics of the law itself.