“Stand firm in the faith"
Paul calls the church to stand firm. Be steadfast. Resolute. To stand our ground and stand on God's Word no matter what circumstances bring. We find these same words in 2 Thessalonians 2:15:
“So then, brothers and sisters, stand firm and hold fast to the teachings we passed on to you, whether by word of mouth or by letter."
Paul calls the church to be courageous. To have courage of heart—no matter the difficulty, danger or pain—to act in accordance with our beliefs. The church is in a battle. God wants well-trained, well-equipped leaders who are courageous enough to live what they believe. Who will step up to the plate and speak up for the church?
Paul calls the church to be strong in the midst of strife and persecution. It's a call to have a strong will, a strong body and a strong mind. To be Capable - Able to move and stand up against all odds. But it's not being strong in ourselves. The strength we need here is a strength beyond what we can muster ourselves. It's God's strength.