The Greek word used here for 'Lord' refers to supremacy.  A 'Lord' was an owner of property and the master of people, somebody who had the right to decide and control.  Used as a title, 'Lord' recognised the person as being in authority and gave a solemn responsibility to serve and obey.  The Bible writers also use 'Lord' as a name for God (Acts 2:47), which greatly heightens our obligation to do what He says today.

This link between words and actions is a fundamental part of God's economy. Words matter, because when God speaks - things happen (2 Peter 3:3-7).  Failure to take God’s Word seriously invites His wrath.  Jesus' question in this verse goes to the roots of human duplicity.  We may say that we honour and serve our Master, but if we ignore His commands, disobey His laws, obstruct His plans and frustrate His purpose ... what kind of words are we saying: surely they are lies.  We might think that we mean them, excusing our disobedience as 'weakness' when we fail to honour the Lordship of Christ.  But that is only another way of saying that we do not really believe that Jesus is Lord.  

The responsibility to obey the Lord’s commands is great.  Our eternal destiny depends upon it.  It is not just the good religious things we do which Jesus notices; it is how we choose to live each day in a way which pleases Him.  Jesus amplified His teaching in Matthew 7:21-23: ‘Not everyone who says to me, “Lord, Lord,” will enter the kingdom of heaven, but only the one who does the will of my Father who is in heaven.  Many will say to me on that day, “Lord, Lord, did we not prophesy in your name and in your name drive out demons and in your name perform many miracles?” Then I will tell them plainly, “I never knew you. Away from me, you evildoers!”’

So, agreeing with the Lord is not enough.  Disobedience demonstrates that our agreement is worthless.  But when we obey, our actions validate our beliefs (James 2:14-17).  More than that, obedience enables the Lord to validate our trust because His words always bring blessing to those who do them.  Alas, busy people may confuse activity with godliness. The question to ask is not, "Am I doing what I think is right?" but "Am I obeying the Lord's words as written in the Bible?" That is why we need a time to be quiet before the Lord each day, to receive His words, agree with them, confess disobedience, and seek His help as we determine to be obedient.  That kind of integrated lifestyle brings a gentle confidence into the home and workplace, as Jesus validates our obedience with His power.