Assalamualikum.
The most powerful ayah is ayatul kursi.I have no idea about scariest ayah.
Anyway,when ones Imaan is weak,it cannot be boosted in overnight. It takes stages and slow process.
First of all,we have to realise that our Imaan is weak. Ahamdulilah you have realised it.
Secondly ask help from Allah, as we cannot help you except giving some advices which might work or might not work.
Third,feed your soul and heart.
Imaan is related to soul and heart. Purify your soul and heart. What is the best was to purify our souls?
Feed your soul.What is the food for your soul?Imaan
You soul is hungry and lack of food.When your stomach is hungry what do you do immediately?You search for food.
Now your soul is hungry therefore search food for your soul.
Food for soul
- Recite Quran frequently and practise what you read
- Memorise quran
- Increase your prayers-do 12 sunnah prayers,wake up at night and do tahajud or qiyam layl prayers.
- Do tawbah whenever you commit a small sin or a big sin
- Give charity as much as you can
- Be nice to everyone
- Control lust and anger
- fast as much as you can
- remember death
- practise sunnah as much as you can
- read the hadith and practise what you read
- Convey Allah's message to others
- Pray Jamaah in mosque as much as you can if you are a male
Our Imaan fluctuates and that is normal.We should strive hard every day to keep it at the highest point in sha Allah.
With my little knowledge, I have shared what I know. I hope others can give you better advice.
Have a worship chart and plan what are the deeds you are going to do everyday.Satan makes us forget. So by hvaing this chart in sha Allah it will help us to do everything we want to do in sha Allah.
P.S: This is not my fatwa,just my advice which in sha Allah might work.
Allah knows the best.
Assalamaulikum