1 Timothy 6:1, (DRB):
Whosoever are servants under the yoke, let them count their masters worthy of all honour; lest the name of the Lord and his doctrine be blasphemed.
Colossians 2:15, (DRB):
And despoiling the principalities and powers, he hath exposed them confidently in open shew, triumphing over them in himself.
The question is so simple:
Could we consider the unbelieving masters Principalities and Powers who did Jesus triumph over them, exposing them confidently in open shew?
That's why 1 Timothy 6:1 says:
lest the name of the Lord and his doctrine be blasphemed.
The idea is so easy, Jesus bought the weak of the world from Principalities and Powers. Or we can say, He bought the weak sinners from the strong sinners. I mean, SLAVERY here is allegorical, weak sinners under the authority of strong sinners.
Strong sinners have the shape of godliness but they are actually hypocrites.
Hence, strong sinners are those who are morally strong, have the shape of godliness but actually they are hypocrites, of no blood and flesh.
While the weak sinners are those who are morally weak. They may be hypocrites or non hypocrites.
I hope it's clear now.