Allah says:وَمَن يَدْعُ مَعَ اللَّهِ إِلَهًا اخَرَAnd whoever invokes besides Allah, any other god,Shirk is the Worst form of Wrong, its Practitioner shall never succeed. Allah threatens those who associate anything else with Him and worship anything with Him. He informs that those who associate others with Allah:لَاا بُرْهَانَ لَهُof whom he has no proof,meaning no evidence for what he says.Then Allah says:وَمَن يَدْعُ مَعَ اللَّهِ إِلَهًا اخَرَ لَا بُرْهَانَ لَهُبِهِAnd whoever invokes, besides Allah, any other god, of whom he has no proof;this is a conditional sentence, whose fulfilling clause is:فَإِنَّمَا حِسَابُهُ عِندَ رَبِّهِthen his reckoning is only with his Lord.meaning, Allah will call him to account for that.Then Allah tells us:إِنَّهُ لَا يُفْلِحُ الْكَافِرُونَSurely, disbelievers will not be successful.meaning, they will not be successful with Him on the Day of Resurrection; they will not prosper or be saved