not for a moment

John Bunyan has a lengthy section in Come and Welcome where he demonstrates how impossible it is that a sinner going to the Saviour for salvation would ever be rejected - the thought shouldn't be entertained for a moment.

If Jesus Christ should allow us once to think that the coming sinner shall be cast out, then he must allow us to question his will, or power, or merit to save. But he cannot allow us once to question any of these; therefore not once to think that the coming sinner shall be cast out.

(1) He cannot allow us to question his will; for he saith in the text, 'I will in no wise cast out.'

(2) He cannot allow us to question his power; for the Holy Ghost saith, He is able to save to the uttermost them that come.

(3) He cannot allow us to question the efficacy of his merit: for the blood of Christ cleanseth the comer from all sin, 1 John 1.

The whole book is devoted to unpacking that one verse in John 6 - 'All that the Father giveth me shall come to me, and him that cometh to me I will in no wise cast out,' and it's done in the most homely and encouraging way imaginable, but in some ways just the title of the book is enough to know: Come and welcome to Jesus Christ. (The verse itself is written above the pulpit in our church, which should presumably make it easier for this congregation to remember anyway!)