I think you walk away from sadducees, telling them as Jesus did, “You are badly mistaken”, and shake the dust from your feet. If someone wants to find God, is willing to say they need God, or is interested in or willing to listen to evidence and says tell me more, and if they aren’t daring you to prove God’s existence to them, having already presuppositionally and resolutely denied his existence in their established worldview and habitual thinking, even denying the existence of the supernatural, that is another case. ‘Preach the Gospel to them’ and tell them why you believe in God and what your experience is and why you know he is real and how he has changed your heart and heart’s desires.
The grounds of [true1] belief in God is the experience of God: God is not the conclusion of an argument but the subject of an experience report.
What’s the main reason, not reasons, on why you are a Christian? - #56 by RoyC
That experience of God does need to entail objective external facts as comprised in the ‘evidence’ link above, but shouldn’t there at least be objective evidence in your mind and thinking to know that you’ve experienced God? I don’t think mere feelings are trustworthy, and they can be manipulated, either by yourself or by someone else.
Here is a pretty potent example of what I’m talking about, the conversion experience of Phil Yancey, not that they need to be this remarkable. From his Where the Light Fell:
1 As opposed to merely intellectual and impersonal academic assent.