"Ministers should love order and should discipline themselves, and then they can successfully discipline the church of God and teach them to work harmoniously like a well-drilled company of soldiers. If discipline and order are necessary for successful action on the battlefield, the same are as much more needful in the warfare in which we are engaged as the object to be gained is of greater value and more elevated in character than those for which opposing forces contend upon the field of battle. In the conflict in which we are engaged, eternal interests are at stake. 1T 649.1"
"Let all things be done decently and in order."
Both passages emphasize the importance of order and discipline. The EGW passage applies this principle to the church, drawing an analogy to a well-drilled army, while 1 Corinthians 14:40 provides a general principle for conduct.
"Thou therefore endure hardness, as a good soldier of Jesus Christ."
Both passages use the metaphor of a soldier to describe the Christian life, emphasizing discipline and endurance. The EGW passage expands on the idea of order and harmony within the 'army' of believers.
Angels work harmoniously. Perfect order characterizes all their movements. The more closely we imitate the harmony and order of the angelic host, the more successful will be the efforts of these heavenly agents in our behalf. If we see no necessity for harmonious action, and are disorderly, undisciplined, and disorganized in our course of action, angels, who are thoroughly organized and move in perfect order, cannot work for us successfully. They turn away in grief, for they are not authorized to bless confusion, distraction, and disorganization. All who desire the co-operation of the heavenly messengers must work in unison with them. Those who have the unction from on high will in all their efforts encourage order, discipline, and union of action, and then the angels of God can co-operate with them. But never, never will these heavenly messengers place their endorsement upon irregularity, disorganization, and disorder. All these evils are the result of Satan's efforts to weaken our fo…
"Bless the Lord, ye his angels, that excel in strength, that do his commandments, hearkening unto the voice of his word."
The EGW passage describes the order and harmony of angels and connects it to the success of their work on behalf of humans. Psalm 103:20 speaks of angels doing God's commandments and hearkening to His word, implying a similar order and obedience.