Can true believers be infallibly assured that they are in the estate of grace

…and that they shall persevere therein unto salvation?

Such as truly believe in Christ, and endeavor to walk in all good conscience before him,[1] may, without extraordinary revelation, by faith grounded upon the truth of God’s promises, and by the Spirit enabling them to discern in themselves those graces to which the promises of life are made,[2] and bearing witness with their spirits that they are the children of God,[3] be infallibly assured that they are in the estate of grace, and shall persevere therein unto salvation.[4] 

1. 1 John 2:3

   And by this we know that we have come to know him, if we keep his commandments.

2. I Cor. 2:12

   Now we have received not the spirit of the world, but the Spirit who is from God, that we might understand the things freely given us by God.

   I John 3:14, 18-19, 21, 24

   We know that we have passed out of death into life, because we love the brothers. Whoever does not love abides in death.
   
   

   Little children, let us not love in word or talk but in deed and in truth.
   

   By this we shall know that we are of the truth and reassure our heart before him….

   Beloved, if our heart does not condemn us, we have confidence before God…

   Whoever keeps his commandments abides in God,  and God in him. And by this we know that he abides in us, by the Spirit whom he has given us.

   I John 4:13, 16

   By this we know that we abide in him and he in us, because he has given us of his Spirit.
   
   

   So we have come to know and to believe the love that God has for us. God is love, and whoever abides in love abides in God, and God abides in him.

   Heb. 6:11-12

   And we desire each one of you to show the same earnestness to have the full assurance of hope until the end, so that you may not be sluggish, but imitators of those who through faith and patience inherit the promises.

3. Rom. 8:16

   The Spirit himself bears witness with our spirit that we are children of God….

4. I John 5:13

   I write these things to you who believe in the name of the Son of God that you may know that you have eternal life.

Question 80, Westminster Larger Catechism