It is in the nature of humankind to constantly slip and fall, to constantly err and sin. But it is the quality of the true Muslim that whenever he sins he makes Tawbah and tries to reform himself.
Consider a person whose occupation is working within a coal mine digging out coal through sweat and hard labour. At the end of every day, his body is blackened with soot from head to toe. Does he tell himself at the end of the day that I will be blackened again tomorrow so I don’t have to wash off today’s dirt and grime? No, he does not. Every evening, he bathes and cleans himself.
It is the same for us when we sin. The Believer cannot tolerate allowing the soot of sin to remain on his heart. So he washes it off with Tawbah.
Allah’s door of forgiveness is always upon to us and Allah loves His servants who turn to Him in repentance.
Sayyiduna Anas Radhiyallahu Anhu said, “I heard the Messenger of Allah sallallaahu ‘alayhi wasallam saying, “Allah, the Exalted, has said: ‘
O son of Adam! I shall go on forgiving you so long as you pray to Me and aspire for My forgiveness whatever may be your sins. O son of Adam! I do not care even if your sins should pile up to the sky and should you beg pardon of Me, I would forgive you. O son of Adam! If you come to Me with sins as great as the earth and meet Me, not associating anything with Me in worship, I will certainly meet you with forgiveness as great as it.’” (At-Tirmidhi)
Adapted from a Q/A on Jamiat.org