Question Summary:
Having respect for a false religion in mind and heart, does this amount to kufr?

Question Detail:

 If a Muslim in the past has verbally said that other false  religions need to be respected and also had respect for other false religions in his heart and mind. And now if he is not sure what type of respect he meant, Whether it was high respect, reverence and high esteem in his heart and verbally OR whether it was worldly respect such as not interfering with them, not causing problems and not using abusive terms and being rude etc.  And he can't come to a conclusion which type of respect he verbally said, had or meant. Does this amount to kufr?

Answer :

There are two aspects to your query.
1)    Reverence and respect for other religions.
2)    Tolerating other religions
As Muslims, we revere and respect only the religion of Islam. It is not permissible for a Muslim to revere and respect other religions.[i]   
The other issue is tolerating other religions. This is permissible and in fact an injunction of the Quran. Allah says,
 وَلَا تَسُبُّوا الَّذِينَ يَدْعُونَ مِنْ دُونِ اللَّهِ فَيَسُبُّوا اللَّهَ عَدْوًا بِغَيْرِ عِلْمٍ كَذَلِكَ زَيَّنَّا لِكُلِّ أُمَّةٍ عَمَلَهُمْ ثُمَّ إِلَى رَبِّهِمْ مَرْجِعُهُمْ فَيُنَبِّئُهُمْ بِمَا كَانُوا يَعْمَلُونَ (سورة الأنعام، ١٠٨)
“And do not curse those whom they invoke other than Allah, lest they curse Allah transgressing without knowledge. This is how we made the deeds of every nation attractive in their sight. Then, to their lord is their return. And he will tell them what they have been doing.” 
In the enquired situation, if the person is feeling guilty for having possibly attributed reverence to other religions, that is an indication of his reverence for Islam. His guilt for possibly attributing reverence to other religions is clear that he meant to tolerate other religions. Accordingly, he did not commit Kufr.[ii]
And Allah Ta‘āla Knows Best
Mehrazur Rahman
Student Darul Iftaa 
Brooklyn, NY, USA