Fear thou not; for I am with thee: be not dismayed; for I am thy God: I will strengthen thee; yea, I will help thee; yea, I will uphold thee with the right hand of my righteousness. (The Bible – Isaiah 41: 10)
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Trust in the Lord with all thine heart; and lean not unto thine own understanding. In all thy ways acknowledge him, and he shall direct thy paths. (The Bible – Proverbs 3: 5, 6)
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Step by step will those who trust Him find that “God is our refuge and strength, a very present help in trouble.” (Science and Health with Key to the Scriptures by Mary Baker Eddy p444: 10, quoting The Bible Psalms 46: 1)
Christian Science Canberra 
sometimes it is difficult to take that initial step over what appears to be a huge precipice and give your trust to an unknown entity. Trust, given wholeheartedly and unconditionally to God is sometimes difficult when trust given to others has been absolutely broken and indeed ridiculed.
Probably the definition of trust. Place one’s faith and existence to someone unconditionally.