The above statement is found in I Peter 3:15. The Christian is to make a determined effort to ensure the truth that God rules in his heart. Jesus condemned those who came with their mouth and lips to honor God while their heart was far from Him (Matt. 15:8). When the Lord God rules in our hearts, the end result is the living of a life which should gender respect on the part of all people. Jesus was dealing with the concern of the apostles as He spoke about His coming death. He then tells them to not allow their hearts to be troubled (John 14:1). The brethren in Colosse were told to allow the word of Christ to live in them (Col. 3:16). In these cases, it is a matter of choice. This is why it must be a determined effort.
Peter continues to tell Christians to be alert and be ready when men would ask them about why they live the way they do. The idea is someone would ask about the reason for our hope. Would we not be able to see from such truth that we are to live our lives in confidence before God and the world. The law of Moses did not have the power to remove sins (Heb. 10:1-4). We are then taught that by coming to Christ we renounce the bondage and accept the truth that God is our Father (Rom. 8:15).
The church has always been plagued by those who operate a secret agenda of one kind or another. Jude called them spots in your feasts of charity (verse 12). If what Jesus taught the apostles in private was to be shouted from the rooftops, the living of what we preach should be just as open. Why some brethren choose to act as if they can hide secret agendas or plans from God is truly amazing. If we have sanctified God in our hearts to rule over our hearts, then our lives should be open for the world to see. Paul wrote about those who were “false brethren” (Gal. 2:4). They are such which serve their own bellies and not Christ (Rom. 16:18). Let us instead have joy in daily serving the King of kings and Lord of lords (I Tim. 6:15).