Before Christ was born, faithful men lived a life of hope based on the promise given in the Garden of Eden: As recorded in Genesis 3:15, God promised He would raise up a "seed" of he woman [Eve] who would destroy satan and his works. (1 John 3:8) From Adam until Abraham, then, faithful men and women looked forward to that seed promised Eve, without knowing very much about the details of what the promise meant.
The ancient Jewish form or worship, the only one acceptable in those days, was fulfilled and/or abolished with the arrival of the Christ; the savior they existed to produce. (Gen 22:15-18; Deu 9:4-6; Gal 3:10-14)