I believe God ‘allows’ Satan because he loves you. He wants you to love Him. In order for you to love Him you must have free will to chose. If He decreed that you love Him, there would be no love, only compunction. As Screwtape said, God can only woo, never complel. He allows you to chose if you will love Him. I would admonish that you Love the Lord with all of you heart, mind, soul, body, and spirit, because while you were in sin (rebellion against God), He still loved you.
“you Love the Lord with all of you heart, mind, soul, body, and spirit,”
Bingo.... that is the first and most important commandment as that is how you find your way through the narrow gate.... with God as your beacon.