How do you know, when it could be that your deceitful, wicked heart is telling you that you know Him, when you actually don’t?
Because the Holy Spirit dwells within me - that is not my "heart" telling me that, nor is it my own deceitfulness - it is the Holy Spirit.
I may not know much, but this much I do know - I belong to Jesus and walk by faith, not by sight.
If you knew the Shepherd, you would know the Shepherd.