You're right.If we do sin the apostle writes:
"My little children, these things write I unto you, that ye sin not. And if any man sin, we have an advocate with the Father, Jesus Christ the righteous:" I John 2:1
In the OT God speaks of 10 times the people tempted God and for that they lost their ability to enter their Promised Land:
" Because all those men which have seen my glory, and my miracles, which I did in Egypt and in the wilderness, and have tempted me now these ten times, and have not hearkened to my voice;
Surely they shall not see the land which I sware unto their fathers, neither shall any of them that provoked me see it:" Num 14:22-23
But, Moses, the man of God only tempted God once when he struck the rock instead of speaking to it.
For them and for us Jesus speaks these words:
"But he that knew not, and did commit things worthy of stripes, shall be beaten with few stripes. For unto whomsoever much is given, of him shall be much required: and to whom men have committed much, of him they will ask the more." Luke 12:48
The key words are "much is given" and "much is required". Moses was given much more than the other children of Israel so he was only allowed the one failure. And we...?
"Verily I say unto you, Among them that are born of women there hath not risen a greater than John the Baptist: notwithstanding he that is least in the kingdom of heaven is greater than he." Matt 11:11
The time of the Baptist was before the beginning of the kingdom of heaven, but our time is another thing, is it not? We have been given more than Moses who was given more than the children of Israel. Have we not also been given more than the Baptist who was given more than Moses?
So then how much is required of us when we have received so much? At what point will God treat us with regard to our "Promised Land" as he did most the children of Israel including Moses?
WE are under the New Covenant which is superior to the Mosaic Covenant.
At what point?
We will Always sin.
If we are IN CHRIST, we will be forgiven.
But God knows the heart.
He will not be mocked...
We must be sincere in our efforts.