Faith is to trust someone. It is also an indication that we are helpless, hence, our faith or trust in the other person to help us. It good to note that faith and doubt cannot stay in the same heart. This is true.
Faith stays with us, when doubt stays outside of us. Faith and doubt are contrary to each other. One doesn’t stay, when the other is present. So it boils down to this – Faith stays where there is no doubt. Doubt thrives where there is no faith.
Also, when place our faith in God, it should not be because, there is no other option for us. That is no faith at all. We should place our faith in God, because we see God as our only way. We place our faith in Him, and in His ability, to keep us safe and secure, because that is the right thing to do
The Bible emphatically and unambiguously states the significance of faith, and its necessity in our lives, as disciples of the LORD Jesus Christ – “6 And without faith it is impossible to please him, for whoever would draw near to God must believe that he exists and that he rewards those who seek him.” – Hebrews 11:6. We must approach God with faith, based and built upon, trust and obedience.
Doubt is different from the questions, that one might have. I would put the difference this way. When we “question” God, it is doubt. When we “ask” questions, we are seeking help for clarity.
Dear brothers and sisters, God is good, gracious and merciful – “19 Therefore, brethren, having boldness to enter the Holiest by the blood of Jesus, 20 by a new and living way which He consecrated for us, through the veil, that is, His flesh, 21 and having a High Priest over the house of God, 22 let us draw near with a true heart in full assurance of faith, having our hearts sprinkled from an evil conscience and our bodies washed with pure water. 23 Let us hold fast the confession of our hope without wavering, for He who promised is faithful.” “16 Let us therefore come boldly to the throne of grace, that we may obtain mercy and find grace to help in time of need…” – Hebrews 10:19-23; 4:16
"Doubt discovers difficulties which it never solves; it creates hesitancy, despondency, despair. Its progress is the decay of comfort, the death of peace. "Believe!" is the word which speaks life into a man, but doubt nails down his coffin."