When the phrase bought and paid for is used, it references something that has been fully acquired with no outstanding debts remaining. Nice car, is it yours? Yes, bought and paid for. This sentiment is true for the Church as a whole and individual Christians. Figuratively speaking, if someone were to look at the church and ask Christ if we belong to Him the Lord can rightfully answer, yes, they have been bought and paid for. When we were lost in the muck and mire of sin, we needed to be set free. However, the price tag on that freedom was astronomical. We were hopeless, having no way to buy our freedom from sin and the death it brings (Romans 6:23). Nevertheless, our Father in heaven loved us so much (Romans 5:8) that He paid the high and requisite price of His Son (John 3:16) to buy us back and secure us for Himself. Therefore, the Scriptures conclude. 

Therefore take heed to yourselves and to all the flock, among which the Holy Spirit has made you overseers, to shepherd the church of God which He purchased with His own bloodActs 20:28. (Emphases MS) 

For you were bought at a price; therefore, glorify God in your body and in your spirit, which are God’s, 1 Corinthians 6:20(Emphases MS)

You were bought at a price; do not become slaves of men, 1 Corinthians 7:23. (Emphases MS)

But you are a chosen race, a royal priesthood, a holy nation, a people for his own possession, that you may proclaim the excellencies of him who called you out of darkness into his marvelous light, 1 Peter 2:9. (ESV) (Emphases MS) 

In every sense of the phrase, we have been bought and paid for. By His sacrifice on the cross, Jesus completely and absolutely bought us out of sin (Hebrews 7:27). Therefore, God has unequivocal ownership of our lives. Our conduct, our speech, or actions are now all guided by thus saith the Lord. It is imperative that Christians understand this principle, for only then can we fully appreciate and comply with the demands of being a servant. In his letter to the saints in Rome, Paul highlighted the imperative disposition of our service.  

Do you not know that to whom you present yourselves slaves to obey, you are that one’s slaves whom you obey, whether of sin leading to death, or of obedience leading to righteousness? But God be thanked that though you were slaves of sin, yet you obeyed from the heart that form of doctrine to which you were delivered. And having been set free from sin, you became slaves of righteousness, Romans 6:16-18. (Emphases MS) When we were owned by sin we were engaged in unrighteousness; now being owned by God we are supposed to be engaged in righteousness. No longer are we walking in the counsel of the ungodly, standing in the way of sinners or sitting in the seat of the scornful (Psalm 1:1). God did not buy us from sin only for us to continue in sin. Certainly not! How shall we who died to sin live any longer in itRomans 6:2

If someone were to come into our homes and take that which does not belong to them, we call it robbery. In the same fashion when we give ourselves to the sinful things of this world we too are guilty of robbing God (cf. Malachi 3:6-9 & James 4:4). To use modern vernacular, we would be robbing God of that which is legally His, our lives. We do not have the right to sin, we do not have permission to sin, and we certainly don’t have God’s approval when we sin. Why? Because we have been bought and paid for by the precious blood of Christ! We are not our own anymore.