Often, we underestimate the power of God's forgiveness in our lives and when we do sin, we condemn ourselves and remain in the guilt of our own sin for some time. God does not want this, instead he wants us to confess our sins to him and start afresh, because we now have full access to a relationship with God because of Jesus who already paid for our sin on the cross.
Guilt is not from God and it is something that Satan uses to put a wedge between our relationship with God, however it is of God when we are firstly convicted of our sin and when our hearts become aware that we have disobeyed God, because when the Holy spirit is convicting us of our sin, he is basically trying to shape us into the person that God wants us to be, which is to be like Jesus his son. Remember, conviction is from God, but then if we cannot then forgive our self after that and when we start to feel guilty, Satan is trying to separate us from God and the love he has for us. Sometimes we have to remember to accept God's forgiveness because if God has forgiven us, then who can justly accuse!
The Bible's answer to overcome the devil when we are feeling guilty is just to confess your sins to God and do not doubt that he has forgiven us, it's as simple as that!
1 John 1:9 'If we confess our sins, he is faithful and just and will forgive us our sins and purify us from all unrighteousness'
Just think of this, once we have confessed our sins and asked for God's forgiveness, God sees us as perfect, blameless, and without sin because of what Jesus has done on the cross. So, let us remember, that it is through Jesus that we are perfect in God's eyes, not by our deeds, but through Jesus.
Romans 8:1 'Therefore there is now no condemnation for those who are in Christ Jesus'.
Always remember the forgiveness that is in Christ Jesus our Lord and remember when we stumble; he welcomes us back with open arms. So let it be his grace that further brings us to serve him and let it be his grace that causes us to constantly turn to him for he is gracious and faithful.