Marks has some additional text: ‘And they were sore amazed in themselves beyond measure, and wondered. 52 For they considered not the miracle of the loaves: for their heart was hardened’ (Mark 6:51-52).
There are some who are seeking Christ, and you have repented of your sin, and you've believed in him, and you’ve felt that first wave of assurance, that you are forgiven, and that you are his, and you have experienced such happiness. And then you have got up a morning or two later, and it's gone. Perhaps you stumble and fall, and sin in some way, and Satan comes and he says, ‘Yes, but if you had been converted, you wouldn't have done that; you wouldn't have said that. You are not converted. What has happened is that you have just assented to Christ. You have said you believe in him, but he hasn't accepted you; he hasn't changed you.’ You are in the position the disciples were in. He is the one we are following; he does great things and marvellous things. But you are not appreciating him. When you had that first wave of assurance and you believed in him, from that time onward, your assignment was to trust in him. He has received you. The one who has moved in your heart, and who has called you; he has forgiven you; he has received you. Think of him. He is God; he is faithful, faithful to his promise. ‘I have believed; I have repented, therefore he will save me, because he is infallible and faithful and God.’
We have got to think! Faith has to be grounded on something. It isn’t just something that floats about in the mind and is ready at hand when you are in trouble, or in need, or you are serving the Lord and you need strength. You must put things together: ‘This is the Lord I serve, who has all power. He is the Lord, who has commanded me to do this. He is the Lord, who saved me and millions of others. Lord, I put these things together and though my situation seems desperate or unpromising, I remain confident in you.’ I ground my faith on what he has done, who he is, and what he has promised to do.