If we doubt God's goodness, does that mean He is going to stop loving us?
If we doubt whether He exists or not at any time, or we therefore forfeiting our standing and our blessings in Christ?
Not at all.
Remember, we are saved by grace, which we receive by faith:
"But God, who is rich in mercy, for his great love wherewith he loved us, 5Even when we were dead in sins, hath quickened us together with Christ, (by grace ye are saved;) 6And hath raised us up together, and made us sit together in heavenly places in Christ Jesus: 7That in the ages to come he might shew the exceeding riches of his grace in his kindness toward us through Christ Jesus. 8For by grace are ye saved through faith; and that not of yourselves: it is the gift of God: 9Not of works, lest any man should boast." (Ephesians 2: 4-9)
The New Covenant is not based on anything that we do, or have done, but everything that Jesus did for us at the Cross:
"22But ye are come unto mount Sion, and unto the city of the living God, the heavenly Jerusalem, and to an innumerable company of angels, 23To the general assembly and church of the firstborn, which are written in heaven, and to God the Judge of all, and to the spirits of just men made perfect, 24And to Jesus the mediator of the new covenant, and to the blood of sprinkling, that speaketh better things than that of Abel." (Hebrews 12: 22-24)
Here is the New Covenant:
"10For this is the covenant that I will make with the house of Israel after those days, saith the Lord; I will put my laws into their mind, and write them in their hearts: and I will be to them a God, and they shall be to me a people:
11And they shall not teach every man his neighbour, and every man his brother, saying, Know the Lord: for all shall know me, from the least to the greatest.
12For I will be merciful to their unrighteousness, and their sins and their iniquities will I remember no more." (Hebrews 8: 10-12)
We look forward to His blessings in our lives, we can trust in His leading in our days, and we can rest assured in His promise because He has paid for our sins, and will never recall them again.
This New Covenant is not enacted because we believe, but rather because Jesus died on the Cross, putting away all our trespasses (Colossians 2: 13) and fulfilled the entire law (Matthew 5: 17; Colossians 2: 14) so that we do not worry about keeping the law, but allow the lawgiver-turned-Savior to keep us.
If we do not believe that our sins are forgiven, however, inevitably we will get caught up in trying to make up for the sense of unrighteousness in our lives; we will try to pay off the sense of condemnation which we sense in our dead flesh.
Jesus has put away all our sins, including doubt (Mark 16: 14), at the Cross.
"Unbelieving" can also mean doubtful.
Yet consider also what Jesus did for Thomas, who had refused to believe:
"Then saith he to Thomas, Reach hither thy finger, and behold my hands; and reach hither thy hand, and thrust it into my side: and be not faithless, but believing." (John 20: 27)
Jesus ministers to us, even when we are doubting. Faith is not something which we conjure up through our efforts, but rather something that we receive as we see Jesus.