1Thessalonians 2:13 For this cause also thank we God without ceasing, because, when you received the word of God which you heard of us, you received it not as the word of men, but as it is in truth, the word of God, which effectually works also in you that believe. 

‘Without ceasing’ – Things we must do without ceasing: [1] Remembering without ceasing our work of faith and labour of love and patience of hope in our Lord Jesus Christ (1:3). [2] We must walk worthy of God, who had called us unto His kingdom and glory and for this cause also we thank God without ceasing (2:12-13). [3] We must pray without ceasing (5:17; Rom. 1:9). [4] We are bound to thank God always for believers’ faith that grows exceedingly and the charity of everyone towards each other (2Thess. 1:3).

‘You received the word of God which you heard of us, you received it not as the word of men, but as it is in truth, the word of God.’ You received the Word of God, not as a fabrication of man, but as being in truth the very Word of God. You have the most total proof possible – the power of the Word of God working effectually in you that believe.

‘Effectually’ [Greek: energeo] energy that puts forth from within effectual operation. Translated “work effectually” (2:13; Gal. 2:8; 2Cor. 1:6); “effectual fervent” (Jas. 5:16); “show forth one’s self” (Matt. 14:2; Mark 6:14); “do” (Php. 2:13); “be mighty in” (Gal. 2:8); and “to work” (Rom. 7:5; 1Cor. 12:6, 11; 2Cor. 4:12; Gal. 3:5; 5:6; Eph. 1:11, 20; 2:2; 3:20; Php. 2:13; Col. 1:29; 2Thess. 2:7). This proves the power of the Word itself in lives of believers (Ps. 19:7; 107:20; John 15:7; Rom. 1:16; 10:17; Heb. 4:12).