Q: After being driven out how did Satan enter Paradise and misguide Adam? If he could enter Paradise, he was not accursed and if he entered in the form of a snake or through any other trick, then God did not drive him away.
A: The garden wherein Adam and Hawwa stayed and where Satan misguided Adam was not the everlasting Paradise (Jannat-e- Khuld), which is promised to the obedient servants of God. So it is useless to ask how the devil entered it. Shaykh Kulaini and Shaykh Sadooq have narrated from Imam Sadiq (a.s.) that the garden in which Adam and Hawwa lived was a garden of this world where sun and moon rose and set. Had it been the Paradise of the Hereafter or had it been the promised Paradise, Adam would not have been driven out of it.
As regards what is said about the arrival of Satan in the form of serpent or in the mouth of a snake, it is incorrect and such rumors are worth less although some have considered them allegorical. For more detail s refer to Tafsir al-Mizan
Sayyid Abdul Husayn Dastghaib