This verse is originally a statement of Paul to Euodia and Syntyche. It is a plead for harmony. Paul wanted them to live in peace and be united in their works, and to stop arguing with each other. It is because they belong to the Lord.
All of us should agree with each other, especially to the Lord. Live in harmony in the Lord. Being in the same mind of Christ means having a Christ-like attitude. Since we are Christians, let us be like Christ. Walk in His image and shine the light!