The sprinkling of Christ's blood was foreshadowed in the Aaronic priesthood by the sprinkling of the blood of sacrifices around the altar. In Ezekiel 36:25 God promised to sprinkle clean water (referring to bodily fluid, not drinking water. See Strong's Hebrew Dictionary.) on Israel to bring them into obedience. God promises to sprinkle many nations (Isaiah 52:15) to compel obedience. Hebrews 10:22 and 12:24 establishes the sprinkling of Christ's blood as the foundation of the new covenant.
When we accept the saving grace of Christ's sacrifice, we instantly take his yoke upon us (Matt. 11:29). A yoke is the symbol of servitude, and the hallmark of servitude is obedience. Obedience always goes hand in hand with the new birth.
We are indeed saved by grace and not works. God's grace gives us the ability and the desire to be obedient to His Word. Obedience is not a matter of works for the true Chrisitan, but an act of praise and thanksgiving. Disobedience does not mean that we can lose our salvation. Consider Eph 1:13 "In whom ye also trusted, after that ye heard the word of truth, the gospel of your salvation: in whom also after that ye believed, ye were sealed with that holy Spirit of promise".
No man breaks God's seal. Romans 11:29 tells us that 'the gifts and callings of God are irrevokable' (NKJV).
Once we are indwelt by the Holy Spirit, can we lose that indwelling? Acts 5:32, "And we are his witnesses of these things; and so is also the Holy Ghost, whom God hath given to them that obey him." A first look would tell us that we could, indeed lose that indwelling. However, the word "obey" (peitharchousin) used here means submitting to an authority or a ruler. Therefore it has the meaning of recognizing the person and authority of Christ and His finished work on the cross. The word obey as used here has no reference to moral commands or to a standard of life but only that we believe in Christ, submitting to His authority. That is the essence of obedience - being submitted to the Lordship of Jesus Christ.