No, God is not the Author of sin, yes God is sovereign, and yes man has free will.
God is sovereign while granting mankind free will. While God could dictate all human events that will take place, He chooses not to. The reason for this should be obvious. God did not create mankind as robots, but as free individuals. God’s sovereignty means that God can do whatever He wants to. He is all powerful, and all knowing and His purposes cannot be overcome.
However, God is also love and His purpose is that mankind has free will to love Him or reject Him. To say that God’s sovereignty means that whatever happens is God’s will makes God partaker of our sins, and this is impossible! Why? Because God’s holiness prevents this! God cannot go against His own nature.
God’s nature is love and the love He wants in return is genuine not like a action figure who string He pulls and the dolls says “I love you daddy”. Of course mankind’s freedom is necessary for the real love that God wants. And while giving us genuine freedom to love Him He must allow us NOT to love Him. To truly be able to respond to His love we must be able to NOT respond to His love.
Love that is forced is not truly love. Love can only be voluntary not forced. God does not break our stubborn will by sheer raw power, but by love! Mankind has free choice and God has not surrendered His sovereignty. His sovereign plan takes into account our fee will.
Some teach that if mankind has to so much as believe (rather than being sovereignly forced to believe) then he is contributing to his salvation. But that’s like saying that if a man gives a beggar money and the beggar holds out his hand to receive the free gift, that the beggar earned the money!
But there is no merit in believing in Christ. Believing in Christ is simply the hand that receives to free gift from God. Christ went to the cross to purchase our salvation, for which He gets all the glory, but which we are responsible to receive.