God desires all people to be saved according to His redemption plan, not Calvinism's compulsion plan. Thus Christ's death was a ransom for all, those to be saved and those never to be saved. Christ became the means of reconciliation for the whole of humanity. Since Christ provided the means of reconciliation according to God's redemption plan, God is not a failure.
False teachers make up falsehoods to disparage others, all the while secretly believing 1 Timothy 2:4-6 does not mean what it says, James 2:5 does not mean what it says, 2 Thessalonians 2:13-14 do not mean what they say, and 2 Peter 2:1 does not mean what it says. Basically they want to change the subject to their false charges, and run from their nullification of God's inspired word.
Here is the truth, Everyone believing into Him shall not perish but have everlasting life. Positional sanctification based on God crediting their faith as righteousness is bedrock gospel. God will accept imperfections in the beliefs and commitments of the lost if His purpose is satisfied. Christ uses imperfect people, broken reeds, to carry out His ministry, such as Peter as taught in John Chapter 21.