"no one can tell by the actions of another person if that person is a Christian". this seems in direct contradiction to many verses in the Bible.
1 John 2:1-29 ESV / 2 helpful votes Helpful Not Helpful My little children, I am writing these things to you so that you may not sin. But if anyone does sin, we have an advocate with the Father, Jesus Christ the righteous. He is the propitiation for our sins, and not for ours only but also for the sins of the whole world. And by this we know that we have come to know him, if we keep his commandments. Whoever says “I know him” but does not keep his commandments is a liar, and the truth is not in him, but whoever keeps his word, in him truly the love of God is perfected. By this we may know that we are in him.
Jeremiah 17:8 ESV / 4 helpful votes Helpful Not Helpful
He is like a tree planted by water, that sends out its roots by the stream, and does not fear when heat comes, for its leaves remain green, and is not anxious in the year of drought, for it does not cease to bear fruit.”
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Revelation 22:14 ESV / 3 helpful votes Helpful Not Helpful[/h] Blessed are those who wash their robes, so that they may have the right to the tree of life and that they may enter the city by the gates.
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John 15:1-27 ESV / 3 helpful votes Helpful Not Helpful[/h]“I am the true vine, and my Father is the vinedresser. Every branch in me that does not bear fruit he takes away, and every branch that does bear fruit he prunes, that it may bear more fruit. Already you are clean because of the word that I have spoken to you. Abide in me, and I in you. As the branch cannot bear fruit by itself, unless it abides in the vine, neither can you, unless you abide in me. I am the vine; you are the branches. Whoever abides in me and I in him, he it is that bears much fruit, for apart from me you can do nothing. ...
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Luke 6:43-45 ESV / 3 helpful votes Helpful Not Helpful[/h]“For no good tree bears bad fruit, nor again does a bad tree bear good fruit, for each tree is known by its own fruit. For figs are not gathered from thornbushes, nor are grapes picked from a bramble bush. The good person out of the good treasure of his heart produces good, and the evil person out of his evil treasure produces evil, for out of the abundance of the heart his mouth speaks.
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Matthew 7:17 ESV / 3 helpful votes Helpful Not Helpful[/h] So, every healthy tree bears good fruit, but the diseased tree bears bad fruit