At any rate the simplicity of the Thessalonian epistles must not be exaggerated. In these letters the great Pauline doctrines, though not discussed at length, are everywhere presupposed. There is the same lofty conception of Christ as in the other epistles, the same emphasis upon his resurrection, the same doctrine of salvation through his death. I Thess. 1:10; 5:9,10.
Undoubtedly the second advent, with the events which are immediately to precede it, occupies a central position in the Thessalonian epistles. A few words of explanation, therefore, may here be in order.
Evidently the expectation of Christ's coming was a fundamental part of Paul's belief, and had a fundamental place in his preaching. "Ye turned unto God from idols, to serve a living and true God, and to wait for his Son from heaven"--these words show clearly how the hope of Christ's appearing was instilled in the converts from the very beginning. I Thess. 1:9,10. To serve the living God and to wait for his Son--that is the sum and substance of the Christian life. All through the epistles the thought of the Parousia--the "presence" or "coming"--of Christ appears as a master motive. I Thess. 2:19; 3:13; 4:13 to 5:11,23,24; II Thess. 1:5 to 2:12.
This emphasis upon the second coming of Christ is explained if Paul expected Christ to come in the near future. The imminence of the Parousia for Paul appears to be indicated by I Thess. 4:15: "For this we say unto you by the word of the Lord, that we that are alive, that are left unto the coming of the Lord, shall in no wise precede them that are fallen asleep." This verse is often thought to indicate that Paul confidently expected before his death to witness the coming of the Lord. Apparently he classes himself with those who "are left unto the coming of the Lord" as over against those who will suffer death. In the later epistles, it is further said, Paul held a very different view. From Second Corinthians on, he faced ever more definitely the thought of death. II Cor. 5:1,8; Phil. 1:20-26. A comparison of I Cor. 15:51 with II Cor. 5:1,8 is thought to indicate that the deadly peril which Paul incurred between the writing of the two Corinthian epistles, II Cor. 1:8,9, had weakened his expectation of living until Christ should come. After he had once despaired of life, he could hardly expect with such perfect confidence to escape the experience of death. The possibility of death was too strong to be left completely out of sight.