The truth is, God is a trustworthy keeper of His promises. His word is sure, and I can rely on His character, ability, and strength to do what He has promised to do. He is dependable with a capital D. This is because of the greatness of His love, grace, and mercy, and not because I merited His trustworthiness by works. This is the truth that the Bible teaches. Thoughts and feelings of doubt and unbelief are lies which the enemy lies to us. We do not have to accept those lies. We can reject the lies and believe the truth instead.
This is how I trained my heart and mind to receive and believe the truth:
“I am feeling __doubtful__, but it is only a feeling brought on by my past. It is not a true reflection of my current reality. My reality is determined by the word of God, and this is what it says: ___ repeat Scripture ___.”
The word of God is powerful, living and active, the weapon of our warfare which is effective against all the lies of the enemy and mighty to tear down strongholds (2 Cor 10:4).