All born again believers in the Lord Jesus Christ hold truths in our hearts that are dear in principle and conviction, but are not always consistently manifested in our attitudes and actions.
There are several reasons for this discrepancy. Let us consider first the possibility of hypocrisy. Believers are tempted to think and say one thing, but do another. How easy it is to assume that because we strongly believe a particular truth of Scripture, we are also faithfully fulfilling the calling of that truth. "My little children, let us not love in word, neither in tongue; but in deed and in truth" (I John 3:18). The Lord Jesus railed against hypocrisy more than any other sin, and we do well to consistently seek His conviction concerning matters in which our confession is not accompanied by conduct. "Cleanse Thou me from secret faults" prayed the Psalmist, and the possibility of hypocrisy should be at the top of the list of such prayers (Psalm 19:12).
It is also true that our convictions are not fully manifested in our conduct because the standards to which we aspire are infinite in their perfection. Believers are being conformed to the image of the Christ whose person, nature, and way are beyond our highest conception of goodness. He was tortured to death, and forsaken of God and man not for His friends, but for His enemies (Romans 5:8-10). We have no frame of reference for such sublime character, but our Lord is nevertheless working to produce the same in us. However, we will not fully attain to Christ's perfection in this lifetime, and thus our aspirations cannot be completely manifested in our actions.
Finally, God's grace and mercy are revealed in His patience with His trusting, but sometimes wayward children. There is never an excuse for sin, and our Heavenly Father never tempts us or leads us to sin. However, the believer's testimony of experiencing God's ongoing forgiveness and cleansing when necessary provides a powerful influence for leading other Christians to the fount of cleansing, and also unbelievers to faith in so gracious a Savior. Honest confession that our conduct sometimes does not coincide with our confession gives us opportunity to bear witness to so great salvation, and so great a Savior. In our present existence and calling to lead sinners to faith in the Lord Jesus, such testimony speaks more clearly than a pristinely perfect life could ever declare. As one young believer once told me, "I know that God never determines our sin. But He sure does take advantage of it by showing us His grace and mercy in a greater way!"
"If we live in the Spirit, let us also walk in the Spirit."