How can a person truly rely on Allah Almighty from within, despite the presence of intrusive thoughts and images that become an internal belief difficult to get rid of?

These thoughts and imagined images are satanic whispers (waswas), and their cure lies in turning away from them and not indulging in them. A Muslim is not held accountable for these whispers; rather, their dislike of them is proof of the soundness of their faith, as Shaykh al-Islam Ibn Taymiyyah said, quoting the Companions' words to the Prophet (peace be upon him): "Indeed, one of us finds in his soul something that for him to fall from the sky to the earth is more beloved to him than to speak of it." He (the Prophet) said: "That is pure faith." Thus, the whispering of Satan, accompanied by one's dislike for it and pushing it away from the heart, is a sign of pure faith. What helps a servant rely on Allah is their knowledge that Allah is aware of them, hearing and seeing, as Allah the Almighty said: "And rely upon the Almighty, the Merciful, Who sees you when you stand [for prayer] and your movement among those who prostrate. Indeed, He is the Hearing, the Knowing."