We should gain eternal happiness

Hence learn the great goodness of God in joining so great happiness to our duty. 

God seems to have contrived all methods to encourage us in our duty; he has not only told us that by our faith and obedience we should escape eternal torments, although indeed, if it were only that it would be enough, one would think, to persuade any man that had the least spark of reason in him, that was not stark mad and had a mind to be always as miserable as he could be; 

but he has done more than this, but has told us that by it we should gain eternal happiness, and he has given us not only encouragement that we shall enjoy happiness after this life, but we shall have God to be our director, our guide while here, and even in this life [he] will be a tender father to us and will keep off all evils that may do us any real harm, and provide for us whatever we stand in need of; 

and yet not only so, but the thing required of us shall not only be easy but a pleasure and delight, even in the very doing of it. 

How much the goodness of God shines forth even in his commands! 

What could the most merciful being have done more for our encouragement? 

All that he desires of us is that we would not be miserable, that we would [not] follow those courses which of themselves would end in misery, and that we would be happy; 

and God, having a great desire to speak after the manner of man, that we should not be miserable but happy, has the mercy and goodness that he forwards us to it, to command us to do those things that will make us so. 

Should we not think him a prince of extraordinary clemency, he a master of extraordinary goodness, he a father of great tenderness, who never [commanded] anything of his subjects, his servants, or his children, but what was for their good and advantage? But God is such a king, such a lord, such a father to us.