Acts 10:34-35
Then Peter opened his mouth, and said, Of a truth I perceive that God is no respecter of persons:
But in every nation he that feareth him, and worketh righteousness, is accepted with him.
God does not show partiality, favoritism for one individual over another when it comes to salvation. Salvation is equal for any and all who fear God and work righteousness will be accepted with God. Yet if God alone solely chooses that only certain individuals can fear God and work righteousness then GOd shows partiality to those individuals over others.
Romans 2:6-11
Who will render to every man according to his deeds:
To them who by patient continuance in well doing seek for glory and honour and immortality, eternal life:
But unto them that are contentious, and do not obey the truth, but obey unrighteousness, indignation and wrath,
Tribulation and anguish, upon every soul of man that doeth evil, of the Jew first, and also of the Gentile;
But glory, honour, and peace, to every man that worketh good, to the Jew first, and also to the Gentile:
For there is no respect of persons with God.
God equally and impartially judges each man according to the type of deeds that man chose to do, whether righteous or unrighteous deeds. It would be partial and favoritism if God determined for certain individuals they do righteous deeds and another unrighteous deeds.
Calvinism HAS God showing partiality, favoritism.