What is meant by being pleased with disbelief and accepting it, and how can a Muslim ensure the soundness of his faith and that he is not pleased with disbelief or accepting it?

Contentment with disbelief means accepting it, choosing it, and feeling at ease with it, as stated in His Almighty's saying: {Whoever disbelieves in Allah after his belief - except for one who is forced [to renounce his religion] while his heart is secure in faith. But those who open their breasts to disbelief - upon them is wrath from Allah, and for them is a great punishment}. So, whoever approves of disbelief or accepts it in his heart and does not denounce it, has consented to it. Examples of this include advising a disbeliever to remain in his disbelief, or sitting in a gathering where disbelief is heard without denouncing it.

The fundamental principle for a believer is to detest disbelief and not accept or approve of it. As long as she is a believer who loves her religion, she will detest disbelief, insulting Allah, and prostrating to idols. This indicates her lack of contentment with disbelief, and doubt or whisperings do not harm her.