In Joshua, chapter three, verse five, the act of sanctification points to the principle that God will not act powerfully on behalf of His people if they are not inwardly clean and aligned with His will. Before we ask God to perform signs and wonders in our midst, we must first be sure our hearts are pure and our desires guided by His Holy Spirit. Joshua gives the instructions for the people to sanctify themselves. However, tomorrow the Lord will do wonders among the children of Israel and to the priests.
The sanctification of the people did not consist in washing their clothes, as in Exodus nineteen ten and fourteen, respectively. In connection with the act of baptism, there was no time for changing their clothes, which might be a substitute for washing, according to Genesis thirty-five, verse two, or abstinence from marital intercourse in chapter nineteen, verse fifteen. This activity was only the outer side of sanctification. It consists in spiritual purification that includes turning the heart to God, in faith and trust in His promise, and willing obedience to His commandments, that they should lay to heart the miracle of grace which the Lord was about to work in the midst of them and on their behalf on the following day.
Today sanctification is more significant than ever for a Christian or believer in Christ. The daily encounters the followers of God engage in are the work environment, social atmosphere, family surroundings, and neighborhood environment. We may need to cleanse our hearts and minds from these areas where we may experience visual, verbal, and listening carnal pollution. Cleaning off the daily dirt from our souls is essential to our spiritual development. Christians should not be careless in their maintenance of keeping themselves clean. How can we hear and connect with God if we contaminate the heart? If only the pure in heart shall see God: this includes us connecting with Him and hearing our prayers and receiving answers.