When the sealing Spirit is called the Spirit _of promise_, does the expression look backward or forward? Is the apostle thinking of the past promise now fulfilled, or of some promise still to be fulfilled? The former, undoubtedly, is true. _The_ promise (the article is significant[53]) is, in the words of Christ, “the promise of the Father.” On the day of Pentecost St Peter pointed to the descent of the Holy Spirit as God’s seal upon the Messiahship of Jesus, fulfilling what was promised to Israel for the last days. When this miraculous effusion was repeated in the household of Cornelius, the Jewish apostle saw its immense significance. He asked, “Can any one forbid water that these should be baptized, who have received the Holy Spirit as well as we?” (Acts x. 47). This was the predicted criterion of the Messianic times. Now it was _given_, and with an abundance beyond hope,--_poured out_, in the full sense of Joel’s words, _upon all flesh_. Now, if God has done so much--for this is the implied argument of verses 13, 14--He will surely accomplish the rest. The attainment of past hope is the warrant of present hope. He who gives us His own Spirit, will give us the fulness of eternal life. The earnest implies the sum. In the witness of the Holy Spirit there is for the Christian man the power of an endless life, a spring of courage and patience that can never fail. II. But there are very definite conditions, upon which this assurance depends. “When you heard the word of truth, the gospel of your salvation”--there is the outward condition: “when you believed”--there is the inward and subjective qualification for the affixing of the seal of God to the heart. How characteristic is this antithesis of _hearing_ and _faith_![54] St Paul delights to ring the changes upon these terms. The gospel he carried about with him was a message from God to men, the good news about Jesus Christ. It needs, on the one hand, to be effectively uttered, proclaimed so as to be heard with the understanding; and, on the other hand, it must be trustfully received and obeyed. Then the due result follows. There is salvation,--conscious, full.