The greetings are addressed "to the church of (the) Thessalonians in God the Father and the Lord Jesus Christ." No such address had ever been written or read before, for the community to which it was directed was a new thing in the world. The word translated "church" was certainly familiar enough to all who knew Greek: it was the name given to the citizens of a Greek town assembled for public business; it is the name given in the Greek Bible either to the children of Israel as the congregation of Jehovah, or to any gathering of them for a special purpose; but here it obtains a new significance. The church of the Thessalonians is a church in God the Father and the Lord Jesus Christ. It is the common relation of its members to God the Father and the Lord Jesus Christ which constitutes them a church in the sense of the Apostle: in contradistinction from all other associations or societies, they form a Christian community. The Jews who met from Sabbath to Sabbath in the synagogue were a church; they were one in the acknowledgment of the Living God, and in their observance of His law; God, as revealed in the Old Testament and in the polity of Israel, was the element or atmosphere of their spiritual life. The citizens of Thessalonica, who met in the theatre to discuss their political interests, were a "church"; they were one in recognising the same constitution and the same ends of civic life; it was in that constitution, in the pursuit of those ends, that they found the atmosphere in which they lived. Paul in this Epistle greets a community distinct from either of these. It is not civic, but religious; though religious, it is neither pagan nor Jewish; it is an original creation, new in its bond of union, in the law by which it lives, in the objects at which it aims; a church in God the Father and in the Lord Jesus Christ.
This newness and originality of Christianity could not fail to impress those who first received it. The gospel made an immeasurable difference to them, a difference almost equally great whether they had been Jews or heathen before; and they were intensely conscious of the gulf which separated their new life from the old. In another epistle Paul describes the condition of Gentiles not yet evangelised. Once, he says, you were apart from Christ, without God, in the world. The world--the great system of things and interests separated from God--was the sphere and element of their life. The gospel found them there, and translated them. When they received it, they ceased to be in the world; they were no longer apart from Christ, and without God: they were in God the Father and in the Lord Jesus Christ. Nothing could be more revolutionary in those days than to become a Christian: old things passed away; all things became new; all things were determined by the new relation to God and His Son. The difference between the Christian and the non-Christian was as unmistakable and as clear to the Christian mind as the difference between the shipwrecked sailor who has reached the shore and him who is still fighting a hopeless fight with wind and waves. In a country which has long been Christian, that difference tends, to sense at least, and to imagination, to disappear. We are not vividly impressed with the distinction between those who claim to be Christians and those who do not; we do not see a radical unlikeness, and we are sometimes disposed to deny it. We may even feel that we are bound to deny it, were it only in justice to God. He has made all men for Himself; He is the Father of all; He is near to all, even when they are blind to Him; the pressure of His hand is felt and in a measure responded to by all, even when they do not recognise it; to say that any one is ἄθεος, or χωρὶς Χριστοῦ, or that he is _not_ in God the Father and in the Lord Jesus Christ, seems really to deny both God and man.