It depends on that person’s relationship to God.

The Apostle James wrote, “If you really fulfill the royal law, according to the scripture, 'You shall love your neighbor as yourself,’ you do well. 9 But if you show partiality, you commit sin, and are convicted by the law as transgressors. For whoever keeps the whole law but fails in one point has become guilty of all of it.” James 2:8-10 (RSV) Therefore, the breaking of any “little” part of God's law of love is considered as breaking the whole law. 

When we commit any sin, the scriptures assure us that the way to forgiveness is through Jesus’s blood.  Ephesians 1:7 (NKJV), “In Him we have redemption through His blood, the forgiveness of sins, according to the riches of His grace.” 

If a person has accepted Jesus as his Savior, has consecrated his whole heart and life to do God's will, and has been spirit-begotten, the justifying blood of Jesus has been applied to him to cover his sins. If this has not occurred, that person is still in the world. The atoning blood of Jesus will be applied to him in the resurrection in Jesus's 1,000 year kingdom.

Justified (righteous) sons of God need to maintain their faith in Jesus. “The just shall live by faith,” Romans 1:17.  If any consecrated believers turn away from Jesus’s sacrifice and deny the merit of His atoning blood, that sin is unforgivable. Hebrews 10:26, 29 (NKJV), 26 “For if we sin willfully after we have received the knowledge of the truth, there no longer remains a sacrifice for sins, … 29 Of how much worse punishment, do you suppose, will he be thought worthy who has trampled the Son of God underfoot, counted the blood of the covenant by which he was sanctified a common thing, and insulted the Spirit of grace?”