Thomas Watson says: “If he is sovereign, why doesn’t he just make some kind of force field around us, so to speak, so that Satan can’t touch us? Temptations are a hard part of the Christian life, so why does our heavenly Father allow us to be tempted?
He lets them be tempted to try them. Temptation is a touchstone to try what is in the heart. The devil tempts that he may deceive, but God lets us be tempted to try us. This is how God tries our sincerity (like he did Job).
By temptation God tries our love. When the devil showed Christ all the kingdoms of the world, and the glory of them, such was Christ’s love to his Father, that he abhorred the temptation. True love will not be bribed. When the devil’s darts are most fiery, a saint’s love to God is most fervent.
By temptation God tries our courage. He is a valiant Christian that brandishes the sword of the Spirit against Satan, and will rather die than yield. The heroic spirit of a saint is never more seen than in a battle-field when he is fighting with the red dragon, and by the power of faith puts the devil to flight.
God allows his children to be tempted so that they may be kept from pride. Pride keeps grace in the heart low, that it cannot thrive. God resists pride; and so that he may keep his children humble, he allows them sometimes to fall into temptation (2 Cor. 11:7).
God lets his people be tempted that they may be more fit to comfort others who are in the same distress, and speak a word in due season to such as are weary. Paul was trained up in the fencing-school of temptation and was able to acquaint others with Satan’s wiles and strategies (2 Cor. 2:11).
God lets his children be tempted to make them long more for heaven, where they shall be out of the range of Satan’s guns, and free from the hissing of the old Serpent. Heaven is the place of rest, no bullets of temptation fly there. Temptations make the saint long to receive the crown of victory in the resting place of heaven.”
-the above quotes were originally posted by Pastor Shane Lems (https://reformedreader.wordpress.com/2017/04/22/why-god-allows-satans-temptations-watson/)