"Bible instruction is to be made forcible by the holy life of the teacher. God-fearing teachers will practice every principle they seek to imprint on the minds of the children. Such teachers do not see their heavenly Father except by the eye of faith; but they have learned of Him; they read His love in the most trying dispensations. They do not judge their Creator by dispensations; they are partakers of His divine nature. They can trust Him who withheld not His only-begotten Son, knowing that with Him He will give all things for their spiritual and eternal good. CT 183.3"
"He that spared not his own Son, but delivered him up for us all, how shall he not with him also freely give us all things?"
The EGW passage directly references the principle of God's willingness to give all things because He gave His Son, as stated in Romans 8:32. It applies this principle to the context of teachers trusting God.