The answer to this and ALL related question is given in 1 John 1:9 -
If we confess our sins, He is faithful and just to forgive us our sins and to cleanse us from all unrighteousness.
Notice that this divine forgiveness does NOT depend on the sin. Thus, God and can and does forgive all sins:
Rom 3:23, 24 - for all have sinned and fall short of the glory of God, 24and are justified freely by His grace through the redemption that is in Christ Jesus.
God can forgive ANY sin; BUT it is very helpful to the sinner to admit they have sinned so that the process of "cleansing from all unrighteousness" can begin as miraculously wrought be the Holy Spirit (John 16:1-9).
As top-shelf examples of this divine grace of God to freely forgive, let me quote a few:
- the apostle Paul was essentially a terrorist; he was forgiven and then became the greatest Christian missionary the world has seen
- Apollos was preaching a "wrong" gospel/theology that was devoid of the Holy Spirit (Acts 18:24-28); when things were explained to him, he changed his preaching theology