The work of God that ye believe (to ergon tou qeou ina pisteuhte). In 1 Thessalonians 1:3 Paul speaks of "your work of faith" (umwn tou ergou th pistew). So here Jesus terms belief in him as the work of God. These Jews were thinking of various deeds of the Pharisaic type and rules. Jesus turns their minds to the central fact. "This simple formula contains the complete solution of the relation of faith and works" (Westcott). Note the present active subjunctive pisteuhte, "that ye may keep on believing." On him whom he hath sent (ei on apesteilen ekeino). The pronominal antecedent (ei touton on) is omitted and the preposition ei is retained with the relative on really the direct object of apesteilen (sent). Note ekeino for God (emphatic he).