From the very beginning Gods mercy has always been for the good of man. Even after many signs and wonders the people chose to rebel against God,yet He did not forsake them (Nehemiah 9:17-21).
Joshua was instructed to be strong and courageous and to serve God just as Moses did,and by doing so God would be with him and not forsake him (Joshua 1:5-7). 5 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. 6 Be strong and of a good courage: for unto this people shalt thou divide for an inheritance the land, which I sware unto their fathers to give them. 7 Only be thou strong and very courageous, that thou mayest observe to do according to all the law, which Moses my servant commanded thee: turn not from it [to] the right hand or [to] the left, that thou mayest prosper whithersoever thou goest.
The only time God would ever forsake any one of us is if we mindfully forsake His ways,as Solomon was told (1 Chronicles 28:9).