John says that we are Children of God and when He (Jesus Christ) appears in the second coming, we shall be like Him. What a beautiful hope we have to look forward to. Because we are children of God and have this hope in Christ, we are encouraged to pursue purity just as He is pure. The false teachers of that time were teaching that one could live sinful lives and still be saved. John says we know the difference between the children of God and the children of the devil by what we practice. As children of God, we have the Holy Spirit which gives us a heart to practice righteousness.