So, 1 Timothy 4:1, what is it that the Spirit clearly says? "That in later times some will abandon the faith and follow deceiving spirits and things taught by demons."

We know that is true, because the Scripture says it, but is there other evidence elsewhere in Scripture that some will abandon the faith and follow deceiving spirits?

Well, we know that in Luke 22, Jesus said to Simon Peter, "Satan has asked to sift all of you as wheat. But I have prayed for you, Simon, that your faith may not fail. And when you have turned back, strengthen your brothers" (v.31-32). We know that Jesus then went on to tell Simon that in spite of his self-confidence that he would remain faithful, he would fail miserably - before the rooster would crow the next morning, he would deny Jesus three times. Heartbroken, Peter strikes out with his sword in the garden, and then seems to disappear into the background until he runs to the empty tomb on Sunday morning. Thankfully, Peter's failure isn't final, and Jesus' prayer is answered. Remember that Jesus anticipates what is about to happen, when he tells Simon, "when you have turned back" to me. So Jesus is also anticipating Simon's return to faithfulness.