إِنَّ ٱلَّذِينَ يُلْحِدُونَ فِىٓ ءَايَٰتِنَا لَا يَخْفَوْنَ عَلَيْنَآ
يُلْحِدُونَ — root ل-ح-د. The concrete sense: to hollow out a cavity towards the side of a pit. The laḥd is the niche opened not at the bottom of the grave but in its side wall (the one dug straight down is called shaqq or ḍarīḥ).
From this the sense of the word follows: not to go straight, but to swerve to the side. Ilḥād — to depart from what is straight.
The picture in the word is worth recording, and I give it as my own reading: the verse describes the defect in the face of the signs not as rejecting them but as shifting them aside. The text stays where it is; the direction is changed.
This fits the forty-fourth verse of the sūra: there it was shown that whichever option had been taken, an objection would be found. Ilḥād is something that can be done without objecting at all.
أَفَمَن يُلْقَىٰ فِى ٱلنَّارِ خَيْرٌ أَم مَّن يَأْتِىٓ ءَامِنًا يَوْمَ ٱلْقِيَٰمَةِ — and a question comes: the comparison is left open, the answer is not stated. The verse leaves the judgement to the reader himself.