Belief is not enough
BiteByte: Not all belief is the kind that saves.
God’s ability to search every heart perfectly means that he knows when someone’s faith is genuine faith that leads to a real relationship with the Lord Jesus and leads to eternal life.
Some belief lacks the power of salvation. This type of faith is only an intellectual acknowledgement compared in scripture to the belief that the spiritual entities known as demons have which only leads them to shudder knowing the day of their judgement is coming.
James 2:20 (AMP) Are you willing to be shown [proof], you foolish (unproductive, spiritually deficient) fellow, that faith apart from [good] works is inactive and ineffective and worthless?
For we are God’s masterpiece. He has created us anew in Christ Jesus, so we can do the good things he planned for us long ago.