Matthew 8:8-9
The centurion answered and said, “Lord, I am not worthy that You should come under my roof. But only speak a word, and my servant will be healed. For I also am a man under authority, having soldiers under me. And I say to this one, ‘Go,’ and he goes; and to another, ‘Come,’ and he comes; and to my servant, ‘Do this,’ and he does it.”
Centurion was the principal professional officer in the armies of ancient Rome and its empire. The centurion was the commander of a centuria, which was the smallest unit of a Roman legion. A legion was nominally composed of 6,000 soldiers, and each legion was divided up into 10 cohorts, with each cohort containing 6 centuria. The centurion thus nominally commanded about 100 men, and there were 60 centurions in a legion. (Britannica website)
If he left the army to become a civilian, he could no longer go into the army, meet with his former centuria and give orders. They would not obey because he was no longer under authority, and therefore not in a position to rule over them.
While Jesus was here on earth , he was under the authority of His Father (Mat 28:18) and so had the authority to command sickness to leave the body of the servant and it obeyed.
When He died and resurrected, as he ascended, he gave to us this authority.
Lk 10:19 I have given you authority to trample on snakes and scorpions and to overcome all the power of the enemy; nothing will harm you.
So let us remain under His authority to be in authority.
Further reading:
Lk 10:22
Joh 3:35
Acts 19:14-17
🙏🏼Blessed day🙏🏼