Are Christians sinners?

[tonychanyt]

Yes, all humans sin and therefore are sinners.

Is it natural for Christians to sin?

I don't think so. Not if you are growing in the Spirit. Christians still sin but it is no longer natural to sin.

If one is born again, he has the Paraclete Spirit dwell in his human spirit. That's his new life from the Holy Spirit. Galatians 2:

20 I have been crucified with Christ and I no longer live, but Christ lives in me. The life I now live in the body, I live by faith in the Son of God, who loved me and gave himself for me.

We have a new life in us. This is a spiritual reality.

2 Corinthians 5:

17 Therefore, if anyone is in Christ, the new creation has come: The old has gone, the new is here!

The new creation is the connection of the Holy Spirit with our human spirit. We did not have it before. No one did before Jesus' sacrifice on the Cross.

Eph 4:

22b put off your old self, which belongs to your former manner of life and is corrupt through deceitful desires, 23 and to be renewed in the spirit of your minds, 24 and to put on the new self, created after the likeness of God in true righteousness and holiness.

Galatians 5:

24 Those who belong to Christ Jesus have crucified the flesh with its passions and desires.

If you have trouble believing this, here is a warning in 1 Corinthians 2:

14 The person without the Spirit does not accept the things that come from the Spirit of God but considers them foolishness, and cannot understand them because they are discerned only through the Spirit.

In this case, try How to get closer to God and grow in faith.