Because;
"Yea, though I walk through the valley of the shadow of death, I will fear no evil: for thou art with me; thy rod and thy staff they comfort me."-Psalms 23:4 (KJV)
So;
"Be strong and of a good courage, fear not, nor be afraid of them: for the Lord thy God, he it is that doth go with thee; he will not fail thee, nor forsake thee."-Deuteronomy 31:6 (KJV)
So;
"Let your conversation be without covetousness; and be content with such things as ye have: for he hath said, I will never leave thee, nor forsake thee."-Hebrews 13:5 (KJV)
But REMEMBER that;
"There shall not any man be able to stand before thee all the days of thy life: as I was with Moses, so I will be with thee: I will not fail thee, nor forsake thee."-Joshua 1:5 (KJV)
And;
"I will not leave you comfortless: I will come to you."-John 14:18 (KJV)
But;
"Teaching them to observe all things whatsoever I have commanded you: and, lo, I am with you always, even unto the end of the world. Amen."-Matthew 28:20 (KJV)