إِذْ قَالَ لِقَوْمِهِ أَلاَ تَتَّقُونَ

(When he said to his people: "Will you not have Taqwa") means, `do you not fear Allah when you worship others instead of Him'

أَتَدْعُونَ بَعْلاً وَتَذَرُونَ أَحْسَنَ الْخَـلِقِينَ

In verse 128, it was said: إِلَّا عِبَادَ اللَّـهِ الْمُخْلَصِينَ (except the chosen servants of Allah). Here, the word used is: مُخْلَصِينَ (mukhlasin) (pronounced with a fathah on the letter lam) which means chosen, elected, people Divinely identified as special. As such, these will be people whom Allah has elected to become recipients of the honor of having obeyed Him perfectly and made themselves deserving of the best returns and rewards from Him. Hence, it would be more appropriate to translate it in the sense of 'the chosen' rather than 'sincere.'