One of the things I dislike about shopping is the trying on of clothes. Why can't there be an international standard of clothing sizes? Instead, I need a large in this, in that an extra-large and in something else an extra-extra-large. I like the things you don't have to try on. Things like toboggans, caps, and ponchos, which are simply "one size fits all."
When Saul finally consented to let young David challenge the giant Goliath, the king of Israel first tried to put his own armor on the young shepherd. However, David could not wear it. He couldn't even walk in it. It was not something he was comfortable with because he had not tested it (I Samuel 17:38-39). That is the way it is with us, sometimes. We try to fit into the roles that parents, friends, family, spouses, or some other man gives us, and it does not fit. We are not made to walk in sin.
On the other hand, in Ephesians 6:10-20 the inspired Paul writes we are to put on the whole armor of God. He tells us what it is, piece by piece. Unlike Saul's armor, this is able to be worn by everyone. This is armor that anyone can be comfortable in.
The girdle of truth: John 17:17 says the word of God is truth.
The breastplate of righteousness: Psalm 119:172 says God's commandments are righteousness.
The shoes of the gospel of peace: Colossians 1:5 says the word of truth is the Gospel.
The shield of faith: Romans 10:17 says faith comes by hearing God's word.
The helmet of salvation: II Peter 2:2 says God's word is how we grow in respect to salvation.
The sword of the Spirit: Ephesians 6:17 says it is the word of God.
You see, to put on the armor of God is to clothe ourselves in God's word! It is to surround and cover our life with His commands and principles. David could not wear man's armor, but we can all wear God's armor. After all, God's armor is One Size Fits All!!! (Matthew 28:18-20; Mark 16:15-16).