Psalms 51:10 Create in me a clean heart, O God; and renew a right spirit within me.
Speaking abut the lust of the flesh -
2Tim 2:19 Nevertheless the foundation of God standeth sure, having this seal, The Lord knoweth them that are his. And, Let every one that nameth the name of Christ depart from iniquity.
2Tim 2:20 But in a great house there are not only vessels of gold and of silver, but also of wood and of earth; and some to honour, and some to dishonour.
2Tim 2:21 If a man therefore purge himself from these, he shall be a vessel unto honour, sanctified, and meet for the master's use, and prepared unto every good work.
2Tim 2:22 Flee also youthful lusts: but follow righteousness, faith, charity, peace, with them that call on the Lord out of a pure heart.
James 1:27 Pure religion and undefiled before God and the Father is this, To visit the fatherless and widows in their affliction, and to keep himself unspotted from the world.
Scripture is speaking about a pure heart for the Lord that we not allow iniquity to reign within our heart (love) for the Lord. The flesh will always sin, but if we are walking in the Spirit you will not fulfill the lust of the flesh, Galatians 5:16-26.