Wouldn't it be gross if you knew someone took a big ole dump then prepared your food and never washed their hands before hand? Well this is a unpleasant thought in the food industry. Yet many a Christian may think they can serve God and be a light to others while having the unrepentent poop stains of sin on their fingers.
"Why do you look at the speck of sawdust in your brother’s eye and pay no attention to the plank in your own eye? How can you say to your brother, ‘Let me take the speck out of your eye,’ when all the time there is a plank in your own eye? You hypocrite, first take the plank out of your own eye, and then you will see clearly to remove the speck from your brother’s eye." (Matthew 7:3-5 )
The truth be told is that we cannot truly be useful for God's service or acceptable to Him unless we are first cleansed by the washing of grace. No matter how intent your heart is on bringing the blessing of spiritual burgers or the crisp fench fries of good works. The truth is our sin can corrupt even the most noble and righteous looking things we can do. So we are first by faith in Christ washed clean when we believe the Gospel, yet a believer can have dirty fingers also if they refuse to repent of some ongoing sin also.
" Come near to God and he will come near to you. Wash your hands, you sinners, and purify your hearts, you double-minded. Grieve, mourn and wail. Change your laughter to mourning and your joy to gloom. Humble yourselves before the Lord, and he will lift you up." (James 4:8-10)
There is of course no sinless disciple of Christ, so repentence is a daily process of self examination and letting The Spirit show us any wrong attitudes, actions or thoughts that we have entertained.
Scripture says in 1 John 1:9 "If we confess our sins, he is faithful and just to forgive us of all unrighteousness"
To confess is more then just saying "yeah I sinned and then going on your merry way flipping spiritual burgers with dirty fingers." True confession does involve acknowleging our sin and agreeing with God but sincerely asking Him to remove the stench and sin from us when we did wrong!