Romans 11:6 says "And if by grace, then is it no more of works: otherwise grace is no more grace. But if it be of works, then is it no more grace: otherwise work is no more work." This means that it'e either 100% Grace or 100% works but it cannot be both or some weird combination of Both. It cannot be 99% Grace plus 1% Sinner's Prayer because Col 4:12 says that Praying is work!

Skeptic A immediately throw in an excuse that says that the Sinner's Prayer is merely the way a person receives the Gospel. 1 Thes 2:13 actually defines receiving as believing.

Skeptic B throws in Luke 18:13 and Romans 10:13 as proof verse for the Sinner's Prayer. Right Division and Dispensationalism and just pure, honest to goodness studying of the Bible can cure that.