We experience the effects of that salvific Covenant in baptism, when we call upon God to be merciful to us, and cleanse us inwardly to live righteously before Him.
And we are strengthened by the graces He bestows on us in baptism to live for Him in the struggles between good and evil in our lives, just as Jesus relied on the strength of the Spirit which led Him in the desert for 40 days. It is this Holy Spirit that helps us live righteously as God works to bring about His Kingdom through us, which even now is at hand.